George C. Scott sighed deeply and glanced at his feet, where the fake fog was steeling onto his shoes in an oily mist.

The prop girls blew powder through the air at his face and a couple of guys behind the camera asked him to mug and turn -- again and again. As the afternoon wore on, with the smog pushing in from outside the theatre and the fake fog swirling up from the stage the camera crew grew noisier, the theater hotter and the tempers more frazzled.

But Scott didn't waver. For five hours of filming a TV ad for "Tricks of the Trade," his grin lasted the same number of required seconds, his feet always hit the right marks and his pofile titled perfectly into camera range.

His wife and costar, Trish Van Devere, watched the media men twistin around Scott like the Lilliputians around Gulliver. "Isn't this ridiculous?" she finally said, moving off to her dressing room and trying to massage the tension out of her neck. "And what does it have to do with the play -- nothing."

Perhaps. The heated and painful minute on sage may have had nothing to do with the play. But is signaled a new episode in the legend of George Campbell Scott -- a new burst of vitality after a difficult decade.

"Tricks of the Trade," a thriller headed for Broadway by way of Hollywood and Washington, opens this Wednesday at the National. Scott, 53, believes it's good play -- he and Van Devere, 39, own a share of it. But most important, he "thinks it will be a hit. The best way you can win this game is to have a chunk of the play and then make it a hit."

The play is only part of Scott's resurgence. Not since 1971, when the actor had "Patton" and "The Hospital" in release, has he had as many commercial projects in the wings. Scott's new film with Marlon Brando -- "The Formula," as commercial a film as Hollywood will see this year -- opens in November. Admittedly, he says, "'The Formula' is a picture that depends more on melodrama and on plot that on character development. But I think it's right to do now." And a fright movie -- '"The Hearse," in which Scott co-stars with Van Devere -- is in post-production.

Scott and Van Devere are also expecting "Tricks of the Trade" to become a hit movie. "We're banking on it, she said, "which is why all of us have signed for at least five months on stage and, along with producer-director George Cates, to do the film as well."

Scott and Van Devere don't say it right out, but they imply that "Tricks of the Trade" and "The Hearse" represent the rare, acceptable projects picked from the fairly dismal range of offers they get a rate of 15 to 20 a month.

"It's esier t tell you what I don't get," said Scott. "And that's good material. A lot of this comes from Hollywood's incessant affection for tend. Films have become not a creative process but an imitative process. You know there was a trend toward big pictures severa years ago. Then there was a trend of $500,000 pictures where everybody was on a motorcycle. Then there was a rash of animal and snake films. And now there are horror films."

The latter trend has led the couple to "The Changeling" (1979) and now "The Hearse."

I don't mind doing scaries," said Van Devere, "if the script is intelligent and right for both of us. That allows it to rise above a particular trend. In "The Hearse' I play a widow who goes off the deep end psychologically. That give the character enough depth to work with."

Both Scott and Van Devere believe their most gratifying projects come from the stage. "For one thing, George is better to work with on stage. cTo tell you the truth, on a movie set he's somewhat of a pill. With a live audience he's a joy to work with."

Off the set, Scott also has a turbulent reputation -- reinforced by his celebrated refusal to accept the 1971 Oscar for "Patton." Asked about the episode 10 years later, Scott said, "When I won the Oscar it doubled by fees at the very least. And how do I feel about that? Wonderful. I don't see any paradox at all between my feelings about the Oscar and about the money that goes along with it. I think all actors are astonishingly underpaid. If I could make $10 million a minute I would still be underpaid." What's in a Name?

"You know, 10 years ago, all we had to do was to put the name of George C. Scott or a Henry Fonda up on the marquee and we would be sold out," said an executive at Hollywood's Huntington Hartford Theater, where the couple opened "Tricks of the Trade" in mid-September. "Now we have to make TV commercials, buy air time and try and get ticket buyers out of the suburbs and down here to see the play."

Scott, like fellow Oscar-winner Rod Steiger, is a paradox to film critics, who have spent years trying to reconcile the talented veteran actor with his bumpy film career. It's true that since he was discovered by Joseph Papp in the '50s -- Scott made his New York debut as Richard Iii at the Shakespeare Festival -- he has made unforgettable films such as "Anatomy of a Murder," "Dr. Strangelove" and "Patton."

But he is equally well-known for costly failures: "Rage" (1972), which Newsweek called "the most pointless film of the "70s"; "Oklahoma Crude" (1973), a movie about oil wildcatting described by The New York Times as a "boomtown that goes bust"; as well as "The Bank Shot," "Crossed Swords," "Islands in the Stream" and "Savage Is Loose." All of them were multimillion-dollar productions that didn't make it critically or economically. m

"It seems like a hopeless list, a simple acceptance by Scott of whatever movie came along first to keep his bank manager happy," said Scott's biographer, W.A. Harbison.

Scott has been talking about financial freedom since 1974, when he made "The Savage Is Loose" with his own and borrowed money, telling reporters he hoped it would be his last film as an actor. But the film was a critical and financial disaster, forcing Scott to star in "The Hindenburg" (1975) for $1 million to save his finances.

Yet for every celluloid turkey, Scott has balanced it with a major success on stage: "Plaza Suite" in 1968; "Uncle Vanya" in 1973; "Death of a Salesman" in 1975; "Sly Fox" in 1976; and now "Tricks of the Trade."

Van Devere, who had already embarked on a career of her own when she met Scott in late 1971, has chosen to put her talent in the shadow of Scott's. They began working together when Scott was No. 5 on the world box-office list and Van Devere had just finished two classics, "The Landlord" and "Where's Poppa?"

She called was to Spain by director John Huston, who needed a replacement for temperamental French actress Tina Aumont in a film called "The Last Run." Scott was appearing in the film with his then-wife, Colleen Dewhurst, but she had finished her part and returned to America. Scott and Van Devere became linked both in Hollywood and in Europe. Scott's marriage to Dewhurst evaporated within a year, and he married Van Devere in 1972, two months after his divorce was final. Since 1973 she has not made a film without him, and she recently described her work as "my career, such as it is."

Van Devere feels that she loses some scripts and roles because of a vague suspicion in Hollywood that she only wants to work with her husband. She also believes that many television shows and movies are "cast only with stars now. Don't get me wrong, I turned some stuff down, but they don't come to me the way they'd come to Faye Dunaway."

She also worries that she may have a low TVQ, or television quotient. "They have a thing out here where they compute your TV quotent, which supposedly decides how effecxtive you are on the small screen. It has nothing to do with your acting ability."

But she is too modest: Her appearance in an original pilot for "Columbo" set a record for prime-time programing several years ago. And one of her made-for-TV films, "Sharon, Portrait of a Mistress," is considered a classic of its genre. Acting by His Rule

Biographer Harvbison believes that Scott is the last of the great independant actors. "Good or bad, for right or wrong, Scott is laying down the terms himself and then acting by them."

Sometimes this has meant disappointment. So far, his plans to pust his stage revival of "Deathg of a Salesman" on TV collapsed because producers wouldn't give him enough money. "It's a wonderful cast," he said, "James Farentino, Teresa Wright and Van Devere" (and Scott as Willy Loman). "They offered me a million dollars to do it. But I wouldn't do it for less than 2 million. I need that to do it justice on television today."

And a script Scott has built around the palgue in London in the 1770s is languishing. "I can't get anyone interested in it," he said. "Maybe I should so it as a musical. I kind of view that project anyway as such a close part of myself, that if I ever got financing I don't think I would last long after that."

But in more commercial projects Scott is as successful as he has been in a decade,although he isn't always comfortalbe with his role. He seems wearied by interviews and by general hype that is now part of selling theater tickets. And one of his public relations men says that interviewers are often disappointed because Scott bears no resemblance to Patton, to Willy Loman or to any of the blustering characters identified with him. "I'm very cold, cerebral actor," Scott says. "When I walk off a movieset I take nothing of the character with me."

Van Devere believes that she and her husband became publicity-shy when they toured the country in 1974, giving thousands of interviews to sell "The Savage Is Loose": "You simply run dry after talking about yourself for the 500th time."

Neither she not Scott will talk about their personal life or differences of opinion. Neither believes that any estatic strains result from their frequent partnerships on stage and in the films. "We don't compete," said Van Devere. "I don't think George views me any differently than other cast members of 'Tricks of the Trade.' It's the public and the press that are always making comparisons."

Backstage at the Huntington Hartford, it is Scott who has an open and friendly reputation with cast members milling in and out of his open door. Van Devere stays more to herseld -- to the extend that technicians almost tiptoe past her dressing room. One afternoon she asked Scott why the crew seemed hesitant to knock on her door. He answered: "Because you terrorize the hell out of them."

But some things never change, and Scott's reputation for temperamental opinions is still secure. He is still adament in his view of the Academy Awards. He began assaulting the Motion Picture Academy for nominating him two decades ago. In 1970 he asked that his name be withdrawn as a Best Actor candidate for "Pattan." The Academy refused to remove his name and Scott won the Oscar, which is still sitting on the Academy shelf.

"I have never felt strongly against the Oscar," he said, "but I have personal convictions that make it impossible for me to live with it. I just prefer not to be involved. The year after 'Patton,' I was nominated for 'Hospital' and I did the cleverest think I've ever done in my life. I kept my mouth shut. It was wonderful. Nobody bugged me. Nobody bothered me. Nobody called men on the phone. Ask my advise if you don't want an Oscar: Just don't go and don't talk."

Van Devere added another dimension to Scott's feud with the Oscar. "I suppose he didn't tell you the real reason, the personal reason he feels that way. It happened when George had only made a couple of films. The first time he was nominated [for 'Anatomy of a Murder' in 1958], he really wanted it. When he lost, it did a bad thing to him and his personal character. He decided he would never let that happend again. And he's right. When you suddenly reflect on yourself going out of balance, it's detrimental to you personally. That's why George feels the way he does about the Academy Awards."

Given Scott's outspoken personality, Hollywood reporters were waiting for explosions on the set when he and Marlon Brando began working together on "The Formula." Both are notorious script-changers and can be tempermental when other major starts are involved. But "The Formula" was completed without even a hint of trouble.

"I loved working with Brando," said Scott. "We got alot swimmingly. He's one of the few authentic geniuses I've ever worked with, and he's also a very sweet-natured guy. I adored working with him, he's such a towering actor."

"The Formula," a Post-World War Ii thriller about a secret recipe for synthetic fuel, was filmed mostle in Europe. And since Van Devere wasn't working at the time, she was able to observe the delicate balance that grew up between her husband and Brando. "Their styles were quite different, but there was an electricity that developed. Each left room for the other.

"I remember once that Brando added a laugh to a very serious scene at a point just before George entered.Brando did it perfectly, letting the laugh run on. But when George came n, he stopped dead -- cutting the laugh off on a split second to clear the air for George."