The local theater owners who had agreed six months ago to pay cash advances for the privilege of showing "Exorcist II: The Heretic" when summer rolled around looked shellshocked Thursday night. So would anyone who had invested sums ranging from $50,000 to $200,00 in a product revealed on the eve of its opening to be a fiasco of stunning, mortifying proportions, likely to bomb out after a single weekend of public exposure and perhaps cause a major scandal in the movie business.

"We're going to need two cashiers," cracked an exhibitor still capable of gallows humor. "One to sell tickets and another to hand out refunds." No one in the local movie community had laid eyes on the picture until a combined invitational preview-press screening-trade screening at the K-B Bethesda the night before it was scheduled to open regular commercial engagements at six area theaters, the Bethesda included.

"Exorcist II" may be the giant-size disaster that finally discredits the practice of blind-bidding for expensive, unseen attractions. Sooner or later something monumentally preposterous and unpresentable was bond to result from this system, and one can understand the consternation of exhibitors stuck with such a turkey - or perhaps one should now say such a locust, because director John Boorman has gotten carried away with locusts, among other things, as both camera subjects and symbols. Theaters playing his new picture may look like victims of locust attacks within a few days.

Columnist Marilyn Beck printed the following item a week ago:

"Filmmaker John Boorman has had to cancel an industry screening of 'Exorcist II: The Heretic,' because - though the $11.5 million film is scheduled for general release next week - it's still not in a condition to be seen." Whatever the motive behind that cancellation, the finished film is still in no condition to be seen.

After seeing what Boorman hath wrought, it becomes pathetically apparent that he was trying to wing it with an obscure conception. The first scene is a veritable omen of disaster: Somewhere or other a priest played by Richard Burton seems to make a mess of an attempted act of exorcism and his subject goes up in flames. Like this ineffectual exorcist, Boorman has dreamed up a would-be transcendental motion picture experience that has turned out to be so pretentiously bewildering that it is [WORD ILLEGIBLE] to be consumed in flames of decision.

I've never heard an audience reject it movie as vocally and resoundingly as the packed house at the Bethesda Thursday night. In fact, the crowd was so unified in its ridicule of a [WORD ILLEGIBLE] endless parade of inexpliable, hysterical or unintentionally funny spectacles that the effect was almost the same as being at a good comedy with a receptive audience.

One should point out that neither William Friedkin, who directed the smash movie version of "The Exorcist," nor novelist-screenwriter William Peter Blatty were associated with this misbegotten sequel. "Exorcist II" seems to have evolved out of delusions of cinematic grandeur shared by Boorman and writer William Goodhart. It's obvious that they wanted to contrive a metaphysical thriller that would be astonishing and spiritually inspiring, but their thought processes are so muddled that the movie degenerates almost instantly into a confounded shambles.

"The Exorcist" wasn't exactly a delight, but it made both commercial and melodramatic sense. Someone at Warners ought to have trembled at Goodhart's premise for the sequel, which begins from the nest-fouling idea that the exorcist played by Max von Sydow failed in his act of self-sacrifice that appeared to save Regan. Pazuzu is back fluttering around while Burton and Louise Fletcher as a psychoanalyst try to get a grip on the little demon by rummaging in Regan's subconscious. Far from taking a new approach, the sequel merely undermines the original.

Intrepid Washington moviegoers can expect a few more laughs than out-of-towners. In the climactic scene the major characters converge on the original mystery house on Prospect Street in Georgetown (reconstructed on a studio set) for what is meant to be an apocalyptic showdown between good and evil. Padre Burton struggles to choose between a good Linda Blair, recreating her role as the once-possessed child Regan, and an apparitional bad Linda Blair who throws him come-hither leers from the bedside.

Simultaneously, a wave of locusts, supposedly captained by the demon Pazuzu, who had invaded poor Regan in the first place, is busy pounding the house to smithereens. Meanwhile, a taxi carrying analyst Fletcher and sadsack Kitty Winn (recreating her role as faithful family retainer Sharon) crashes into the front yard.

All this commotion somehow fails to rouse the neighborhood (they've seen everything in Georgetown?), at least until the fadeout, when curious extras belatedly materialize and reduce the audience to helpless mirth one last time. By then you're wondering if the whole apocalypse could have been a figment of the Fletcher character's deranged imagination, just as you wonder earlier if several baffling episodes set in Remotest Africa are meant to be taken literally or shrugged off as figments of the Burton character's deranged imagination.

After all, these characters seem to spend the entire movie exchanging misconceptions and misjudgments while the poor, exposed actors exchange excruciating lines.

Every time Fletcher gets to drone something like "Those bad dreams are still inside you, Regan; there's a machine we can use together to get them out," Burton seems to come right back by moaning something like, "Does great goodness draw evil upon itself?" or snarling something like, "I'm not obsessed! I'm not!"

The killer-diller for Washingtonians is the sight of Burton and Blair walking away from the devastated house in the general direction of Rosslyn. Given local topography, they would have to be walking on air. If Fletcher isn't having delusions, we certainly are.

In the lobby afterwards people resembled the first-nighters at "Springtime for Hitler" in "The Producers." Perhaps Warners should change the title to "Springtime for Regan" and hope that the movie public also decides to misconstrue it as a put-on.