I DON'T THINK even Gloria Steinem found much to get mad about at last night's Pudding opening. It's not that the folks on Holyoke Street have given up their traditions of adolescent sex humor, bathroom jokes, and Gold-Coast-sensibility wisecracks. They've half-heartedly tried to keep appearances up, in fact. But the first night was so obviously harmless that it would take a lot of effort to be offended at all.

Bewitched Bayou was dull, though, and unless Bill Strong can re-write his book and lyrics into some better kind of shape, it's going to be a long-running clinker of a musical. Pudding shows were never supposed to get too wound up in the intricacies of plot, but Bayou's is stretched so thin it snaps between a few of the scenes.

Early on in the first act, this season's femme fatale, a witch named Helza Poppins, starts casting spells on a Greek shipping magnate (Pluto Cratopoulos), a Canadian Mountie (Major Assburn) and his troops, Assburn's liberated-bopper of a charge (Mary Wanna), a hefty schoolmarm (Hortense Prune) and her maidens, One-Eyed Jack and his faithful Indian Toronto, two refugees from the frontiers of the 1840s. While they're all stomping around in Helza's "enchanted forest," Strong's unflattering imitations of Shakespearean romance require that they fall in love with each other in various un-lovely combinations until the last scene matches them up in their rightful (but still bizarre) combinations. This is all happening in Louisiana, remember. No matter how hard I remind myself that it's supposed to be un-serious music-hall theater, I can't help warning you that Bayou's book is (even for a Pudding Show, now) well... eccentric. I suspect some of the one-liners wouldn't make sense if they had footnotes.

TO MAKE MATTERS worse, even Ronald Melrose's score is hardly ever better than its lowest points. He can borrow a few bars from Handel, a few more from Richard Rogers, and a tempo from Sir Arthur Sullivan, but when the band gets back to Melrose's score, it's slow going again. Still, it's the kind of show kindhearted audiences try hard to like, and the cast is already learning how to spread its limited talent thin. David Lewis does reliably unflappable matron Prune, waddling through both acts with his dignity intact even when his virtue has been lost. As the traditionally breathy and breasty torch singer, Tom Wells (Helza) has enough slink and alto in him to fill his shining jump-suit with credibility, and Mark Miller's One-Eyed Jack starts out as the most convincing and most spirited character of the whole, unsure crew.

There were two bright spots last night in this otherwise dim prospect. One was a spin-off from Busby Berkeley's elaborate choreography, done with spinning transparent umbrellas, none the worse for having been lifted from last Fall's Exproduction of Dames At Sea. The other (and the only satire with any bite) is a runaway mix of The King and I and Chinese Revolutionary Opera called "The People's Opera Glorifying Revolutionary Heroes One-Eyed Jack and Toronto." With Red Flags and posters of Mao, it plays the stereotypes to the hilt, and with saving grace, perceptibly manages to suggest that Nixon and Kissinger were conned like a bunch of yokels last year by the ceremonious hoo-hah of their Chinese hosts.

An experienced coach would declare this year's Pudding show the product of a "building season" and pray for some more talent next year. But this season's creators and producers of Bayou were cracking thier knuckles with more than first-night jitters in the back row last night, and they may have to for a while to come. With a little work, director-choreographer Voigt Kempson can probably add some stage business, get the Mounties and Maidens to stop moving their lips to count out their steps and maybe even get them to dance with a little class. Until he does, it's going to be an only occasionally engaging, generally awkward production. Those who don't mind the peculiar taste of the average Pudding effort can at least have their quota of hairy-chested Woodnymphs and Sprites. But if you have only one Pudding Show to see in your lifetime, you should have some second thoughts about this one.