What is it like to be the spokesman for Metro when the trains crash or the tunnels flood? Or Con Ed. when the lights go out? Does Bert Lance's spokesman ever have a nice day?What was it like answering question for Marvin Mandel? Or Spiro Agnew? How is the Korean embassy press officer holding up? How about Barry Zorthian's stomach-wrenching ordeal for four years as the U.S. spokesman in Saigon?

All those glaring lights and live microphones and pushy reporters, all that . . . hostility . . . who needs it?

Life as a spokesman whose jon includes bearing bad tidings or defending unpopular causes or personalities under siege has its disadvantages the extent of which depend on the precise circumstances. Con Ed's man has been with the company 19 years, while VIc Gold, one-time Agnew spokesman, decided he'd caught enough grief and quit spokesmanship altogether. Uniformly, though, these unenviable jobs require extreme tact and patience, a cast-iron stomach, ability to withstand pressure for long streches, a willingness to infuriate friends and family, in short, durability and a thick skin.

Cody Pfanstiehl displays the perfect temperament for his combat post as Metro spokesman. He's doggedly cheerful - always as it were, viewing the water glass as half full while others see it half empty. "The flood," he says of Metro's recent underground leak "had a Noah and Johnstown popular appeal to the press. The water was 18 inches."

From the time he heard there was water in the tunnel - his two-way telephone beeped while he was delivering a speech about the smooth-functioning Metro - until the problem was fixed days later. Pfanstiehl, sleeping not at all the first night and little after that, spent almost all his time patiently, but interminably explaining what went wrong, what routes were changing, and when Metro might reopen fully.

To be a good spokesman under such duress, he says, one first must know what he's talking about. Pfanstiehl knows much about Metro, literally from the ground up, having blazed new trails in excavation muck white leading uncounted tours over the years of tunnels under construction. But there's a limit to how much a harassed spokesman can endure.

"I got a call at 2 in the morning," he says "from a woman on Eve Street, when they were building there, complaining about noise. She wanted to know exactly what they were doing, how they were right outside her window and disturbing her, and what a dummy I was. I was the information person and I didn't know exactly what they were doing. I said, "Lady, why don't you stick your head out the window and ask them?'"

But then it could be worse for Pfanstiehl: He could be Bert Laance's spokesman and face large, ugly headlines every day. Until May, Bob Dietsch was an economics and business writer for Scripps-Howard newspapers. Then he signed on at the Office of Management and Budget. Then came trouble for Lance and long days for Dietsch.

But despite being in a tough spot, Dietch maintains the necessary cool, admitting only that, yes, he does put in some long days but that, "We still get OMB questions" and "I'm just surprised at how optimistic my boss is. He says he's going to sweat it out. Every day he comes in here smiling."

And that, for the record, is the posture at the Korean embassy, where it's the job of Su-doc Kim to field questions about Tongsun Park and Korean lobbying activites.

"This is a loaded question," he said when asked how the ongoing story has affected him. "When you have a hot issue, radio, television, and newspapermen call. That's understood. I don't count the number of calls. I just grab them as they come along. As a press officer, you don't expect something quiet."

Kim spent two years as press officer in London before coming to Washington. And how was London? "Relatively quiet to my stint here," he says.

Quiet, relatively speaking, was how it was at Consolidated Edison of New York, too, before the power failed July 13. William Farley, director of public information, arrived at his New Jersey home after work to find phone calls backed up and more pouring in.It was 4 a.m. before he could break away long enough to make it back to the office. "There were several days when people had their heads on a pillow an hour at a time," he said.

But if Farley thought he was busy when it was dark, he realized when the lights came on a day and a half later that his work had only begun. He says it hasn't stopped; Con Ed is the subject of a number of investigations that require the reading of materials and responses. And that says nothing about criticisms that, Farley observes, "come in from left field," unexpectedly. "Nobody calls us and says, "We're going to blast you today,'" but he notes that Con Ed has come in for some harsh words during the New York City mayorality campaign.

But for sheer durability in the most trying of circumstances. Barry Zorthian is the model spokesman, one who was cited for the longest continous service of any senior American official in Vietnam when he left in 1968.

"There had to be some relief getting out of that pressure cooker," he said. "There were some very difficult times." And Zorthian was putting it mildly. It was he who had to announce the first air strike into North Vietnam as well as numerous setbacks.

"Tet was as bad as we could have in one day," he said. "The attack started at night. I was on the phone all night. In the morning we went to the embassy. There were bodies in the area, VC, some Marines. It was not a very salutary setting for a balanced account of the war."

Zorthian says "the revolving-door government of Vietnam in the year of 1964 and into '65, depending on how you count . . . they had eight or nine governments." It made it difficult for him "to persuade anybody there was a viable Vietnam government on our side."

But for all the heartache in his work, missing his family, he says, was worst of all. His wife and two teen-age sons were with him at the start, but shortly moved to the Philippines, where he tried to spend one day a month. Looking back at the time he could have spent with them had he been in another line of work, he says, "I miss those years."

As troubled as much of his time was, Frank A. DeFilippo, former press aide to Maryland Gov. Marvin Mandel, says he has no regets about his seven years in Annapolis before he became an advertising executive in Baltimore. In fact, despite Mandel's problems, the job adjustment was severe for DeFilippo.

"When I left there," he says, "Ifelt like I'd been lobotomized. I didn't know whether was there or here."

DeFilippo says he loved his work and, by his account, relished the give and take with reporters delving into Mandel's administration.

"The most difficult thing I went through," he says, "was that Jamaica trip (Mandel took) in January 1975. I can say with a clear conscience that was the only time I was left out on a limb. I didn't know (the details of the trip). I got caught in a lie.

"But dissembling and hedging is part of the job. You've got to dissemble, fudge. It's a question of wits. Can you outsmart a reporter or can't you?"

With Vic Gold, it was a question of trying to persuade Spiro Agnew as Vice President to meet the press while tactfully trying to portray him in the best light. It proved futile. "He had built up a wall of armor against the press," Gold said. "He was hostile to the press. If I tried to be an accurate spokesman I'd be saying screw you to everybody.

"The most difficult period was right after the 1971 round-the-world trip. It was described as a PR disaster. We were bombed in the press. I tried to persuade him to go on TV in rebuttal, accept the longstanding offers we had. He resisted. I threatened to resign. Finally, he went on 'Issues and Answers.' But it was six weeks later. Nobody cared about the trip then."

Feisty and seemingly tough-skinned, Gold, a Washington correspondent, says now of Agnew's disdain for the press, "It tore me up." When he got back from the world trip, he said he decided, "I'm going through '72 (the campaign) anyway, but I gotta really get out of this thing."

Gold says that when he went in to say good-bye to Agnew, Agnew asked him, "What would your advice be to your successor?"

"I told him my advice would be to keep the guy completely informed. That day at 9 a.m. something (had come) up I didn't know about. But he said (in that situation) you just tell 'em you don't know. I tried to tell him that makes him look bad, not me. He said, 'You're just trying to maintain your popularity with the press.'

"I stood up and said, 'I don't have to take this s. . .'" And that was the end of Gold's career as a spokesman.