I WAS GOING TO take the high road, be the Father Flanigan of film criticism, and say there is no such thing as a bad movie, that standards are relative, tastes differ. Then I saw "Rollercoaster."

"Rollercoaster," slambang title notwithstanding, is a singularly tepid piece of work, so dull not even Sensurround can keep you fully awake. Yes, I cried when it was finally over, there is such a thing as a bad movie, and this it it.

By the next morning, I'd calmed down, decided "Rollercoaster" had its virtues after all, and was maybe even marginally entertaining. And that flipflop is the bad movie problem in its essence: While intellectually we know that ultimate determinations of good or bad may take decades to work out, and may change decades later, the way the theatricality of D. W. Griffith's silents goes in and out of favor, emotionally we often cannot resist flatly saying that what we dislike is bad, bad, bad.

Minor key pet peeves like warm-hearted films about concentration camps aside, bad for me falls into two diametrically opposite groups: the intellectually pretentious and the insipidly pandering.

Though most people, even a recent worldwide poll of critics, think Antonioni's "L'Avventura" some kind of cinematic masterwork, its vacuousness has always left me the wrong side of bored, trying to figure out why the ennui of aristocratic Europeans is supposed to stir my soul.

Ditto for Dennis Hopper's dreary, muddled, self-indulgent "The Last Movie," which aggravated me so much when I saw it that I threw a raw carrot at the screen. (I missed.) As William Burroughs once wrote in a somewhat different context, "I am not innarested in your horrible disease."

This type of pseudo deep-think movie has now become the exclusive property of what critics like to call The New Young German Filmmakers. All the actors in the latest Werner Herzog film, "Hearts of Glass," for instance, were hypnotized to within an inch of their lives, and looked it. Instead of reacting to this kind of "I Walked With a Zombie Revisited" filmmaking the way any normal audience would, esthetic-minded writers have taken to justifying it as "an experience," "an interesting experiment" and worse.

All this does not mean that "audience pictures" are free from faults, though bad popular movies are harder to work with since film is basically a popular medium and since may people find all sorts of virtues in what have come to be called "good-bad movies" or "movie-movies."

What is genuinely bad here tends to be in the area of, forgetting Mencken for a minute, underestimating the public taste, of confusing overkill with effectiveness.

A film like "The Exorcist," for example, failed because it laid nausea on with a trowel, hoping no one would notice that sickening isn't the same as frightening. On the other side, both "Butch Cassidy" and "The Sting" were so calculatedly, cloyingly cutesy as to inspire nausea of a different sort. The problem is not that people won't respond to quality escapist entertainment - huge successes like "Star Wars" prove they will - it's that they're hardly ever given the chance to chose.