Could it be that baritone Robert Merrill feels ill-used by the current Metropolitan Opera management? That, one gets the idea, is among his reasons for writing this silly, nearly likable trashola about a commercial TV network's idea to devote all of prime-time every Monday night to live Met broadcasts, with ""three commentators much in the style of Monday Night Football."" The plot hook: which seamy soprano will TV exec/stud Sandy Goldman (""only one notch below Robert Redford"") choose to be the singer commentator? Overweight, indiscreet, alcoholic Gloria January? Vocally deficient but gorgeous Carla Scarlatti, with a homosexual husband and dabblings in porno flicks? (Hi there, Anna Moffo.) Or that evil climber Elizabeth Anders? Before the big decision is made, each of the ladies' secret lives is aired; Sandy impregnates and weds Carla (""I can't believe it. A child with Carla Scarlatti, the most gorgeous and talented woman in the world. Wow!""); Elizabeth viciously steers reformed Gloria back to the bottle; and Merrill gets the chance to throw darts at the Met's music director and stage director (fictional names, obvious models): at one point, Gloria shouts, ""I should sue you for conspicuous lack of talent and for cultivating a garden of pansies in what used to be an opera house."" For all the name-dropping and off-the-cuff chatter (""That's what technique is, General, the ability to sing 'Vissi d'Arte' flat on your ass with a throat full of snot""), this has far less authenticity than last year's Aria. But, taken with a semiquaver of salt, it's an almost nostalgically vulgar helping of glittery garbage--and some good, stupid, nasty fun.