FOR AGES, dance was the underprivileged art, lacking the popularity, the acceptance, the mystique and the credibility of its cultural kin. Time was when you couldn't give tickets away to even the best dance events, and when Danskins really were for dancing - only.

That has changed now, as the world has amply noted. The mere mention of a big name and the groupies start lining up for standing room at 2 a.m. the morning before the box office opens. Dance is In, dance is Big, and dance is still taking show business, the movies, the media and the audiences by storm.

The so-called "explosion" is very largely a public-relations phenomenon, nevertheless. Dancers and dance companies are better off than they were, but survival in the dance world remains very much a matter of brinkmanship.

So, while the sun shines, the dance community had been trying to make as much hay as possible. Hence the boom in dance photographs, dance souvenirs, dance T-shirts, dance record albums, dance figurines, dance stamps, dance boutiques, even dance board games.

The most conspicuous evidence of the newfound desirability of dance, however, has been the epidemic of dance imagery and allusion in commercial advertising. Of course, dance is tailor-made for such exploitation. In an age which emphasizes youthfulness, sensual awareness and physical prowess to start with, what field could provide richer provender than an art which rests on beautiful bodies beautifully toned, soaring sleekly through the air and forever evoking an aura of sexuality on the one hand, and ethereal romance on the other.

In any case, the Madison Avenue hierarchy can smell a potential money-maker parsecs away, and went into spirited action the moment it became clear that dance had "arrived" as a viable selling point.

Perhaps the wave crested with the August-September issue of Modern Bride magazine, which bears on its cover an inset photo of Leslie Browne kissing Mikhail Baryshnikov's bare shoulder in a frame from the movie, "The Turning Point."

Inside, one finds a three-pronged attack: a lead article on bridal fashions, 20 pages pegged to "weddings inspired by the dance," showing nuptial gowns against a background of School of American Ballet students in plies and penche arabesques; a five-page story about Baryshnikov which talks of this "sensual Russian luminary" as "a quicksilver of grace - fused to passion, and undeniably sexy"; and, in the "Beauty" section, a two-page picture spread on dance exercise headed "Turning Point to Beauty and Health."

What amounted to a saturation campaign in perfume advertising started last fall with the introduction of "Pavlova," a "never before fragrance," and it's still going strong in big city dailies. The opportunities offered by the illustrious dancer must have blown the copywriters' minds, because the various "Pavlova" displays make a richly amusing study in the taxomomy of hype.

Bloomingdale's came on, for example, with "Pavlova. Created in tribute to the spirit, drama and romance of the legendary ballerina.A joyful blend of tuberose, jasmine, rose and hyacinth. Perfect for the woman who enjoys creating her own legend." B. Altman countered with "Because you deserve to live in a dream . . . This is the sort of fragrance women wore in Paris then, when Pavlova was the world's prima ballerina. Here is Pavlova, not for all women. Not for all times. Only when you want your heart to dance."

Macy's, surprisingly, was almost restrained by comparison: "Anna Pavolva Prima Ballerina extraordinaire. The toast of Paris in the '20s . . . It's the fragrance that bears her name. Haunting. Romantic. A scent that creates its own ambience. Pavlova. A star is born again. Pavlova Parfum." But Saks Fifth Avenue burst forth into poesy: "Arms that flutter and turn to wings - Air that clouds and turns to plumage - Swan that turns . . . there! swan-to-raven - White that's pierced and turns to red - Pavlova to swan to legend to fragrance."

Perhaps the most astonishing thing about this deluge is that not one of these ads sported a picture of the actual Pavlova - some had tutued models in "Dying Swan" poses, some had just the shoes, and some merely perfume bottles. But a December, 1977 ad for Bal a Versailles - "a beautiful effusion of fragrance that's at once mellow and light . . . yet deep and mystical, too. Ravishingly romantic. And totally luxurious, etc., etc.," went on a reality trip - a moody photo of Patricia McBride of the New York City Ballet waltzing with her dancer husband, Jean-Pierre Bonnefous.

Some of these ads work by subtle indirection. Last month, Saks Fifth Avenue ran one that began: "Release yourself . . . with the sheer, summer energy of Cristalle. Because now, the feeling, the life, the whole terrific ambiance of summer comes into play. And that means teeny bikinis and jogging shorts. Exercise. Waldorf salads. Sports. The beach! Summer's here at last. And for that - one needs a fragrance with the brilliance, the sparkle, the pure sunshine of Cristalle by Chanel." Only the large accompanying photo showed a girl on the beach, not in a bikini, not in shorts, but in a leotard, praise be. Even more tenuous in its dance connection was an earlier Lord & Taylor ad for a cashmere "smockcoat" that had a blurry, soft focus background shot of the Scarf Adagio from "La Bayadere."

Some stores are dedicating whole rooms to dance-inspired fashions, and not only those stemming from high art, of course. Under a picture of a Travolta look-alike, Abraham and Straus in Brooklyn is now touting its new Night Fever shop, along with a suit that "everybody is a star in." Not to be outdone, in its own more tony way. Bloomingdale's in Manhattan has been promoting a "First Position Shop" with a shot of tots at a studio barre and text that reads, "Everything you need for dancing, for gym, for dreaming your dreams of stardom."

It's not just wearables and cosmetics that have jumped on the bandwagon. Publications, too, have been pushing dance. In a full-page newspaper ad promoting its cover story on ballerina Gelsey Kirkland and the nation's ballet madness, Time magazine employed the reflected glory technique:

"An engrossing portrayal, not only of a brutally demanding discipline, but also of that most awesome of all human varieties, the totally dedicated artist. Another reason why millions more readers prefer Time each week." The logic here is a bit skimpy, but who's scanning syllogisms in the heat of such passion?

Horizon magazine has gone in for the superstar testimonial - Rudolf Nureyev pictured smiling over the quote, "A theatre full of Horizon readers is one of the best audiences I can imagine," a thought that no doubt struck him at random while shaving one day.

The following ad copy didn't save "The Trib" from swift extinction, but it takes the cake for ingenuity: "If Margot Fonteyn were a newspaper, she'd entertain like The Trib. Fascinating. Sensitive. Precise. Intriguing. Coming January 9th. Every weekday morning. The Trib. It should have happened sooner." Television, you may well imagine, has not been sitting idle through all this. There's one particularly persistent spot at a late-night hour you may have seen, for instance, wherein a woman in practice clothes cuts a few ballet steps towards the screen and then stops long enough to tell you about the advantages of Johnson & Johnson's new tampon.

Sometimes you can see the mental gears grinding, as the copywriter tries to figure out how to satisfy an account's demand to get into the dance act. There's the Breck ad, for instance, picturing a young woman in leotard and tights, holding a pair of toe shoes over the back of her chair and saying: "After years of dancing, I was naturally the girl with the legs. Until I started using pH balanced BRECK creme rinse. Suddenly my hair is getting all the attention." You see how easy it is - from feet to head in one easy flip.

The favorite among fiendish non sequiturs was a full-page color spread in The New Yorker some months back that showed a ballerina in pique arahesque next to which, in large type, was "I'll bet they don't wear shoes in Kentucky." In smaller print, the body of the ad continued, "You're right. Sometimes we wear ballet slippers. Or riding boots. Or water skis. It just depends on how we're using our leisure time. And in Kentucky we've got plenty of ways to use it."

It turns out to be an image-building ad for the state of Kentucky, an attempt to combat the backwoods yokel stereotype with its supposed opposite, paid for by the state's Department of Commerce.

I'm not complaining, mind you. If this is what it takes to bring the pleasures and rewards of dance to the center of attention, let's have a few more fragrances, shampoos, and breaded chicken wings - it's all in a good cause.