Bob Guccione's miserable cinematic toga party, "Caligula," is a profligate, overpriced reenactment of the brief reign 737 A.D. to 41 A.D.) of Rome's most degenerate emperor. By and large it is an appalling bore. Having sank a reported $17.5 million (about $9.5 million over the original budget) into this enervating Roman scandal, the esteemed publisher of Penthouse and Forum evidently hopes to recoup by charging extravagent admission prices while renting theaters for special engagements. The $6 toll at the Georgetown seems fairly outrageous; but it represents a $1.50 markdown from first-run prices in New York.

Since hope springs eternal in the gullible human breast, it's almost impossible to convince people that they might not get their dollar's worth of vicarious depravity from an attraction as notorious and expensive as "Caligula." Nevertheless, here goes. The crucial question for potential suckers is whether five or six minutes of hard-core sex is worth the remaining two hours and 30 minutes of inert costume melodrama, "relieved" only by the occasional graphic atrocity.

It appears that Guccione himself added the hard-core tidbits after firing the original director, an Italian hack named Tinto Brass, and replacing him with a pal named Giancarlo Lui. Without these inserts, the sensational footage would recommend itself almost exclusively to connoisseurs of the morbid: disemboweling, beheading, castration, a gallery of naked freaks, torture, a little necrophilia, a little urolagnia, a vomiting scene in close-up And slow-motion, infanticide by head-bashing of nauseam.

By comparison, mere hard-core sex-play looks relatively innocuous. Guretone recruited former Penthouse centerfolds in this belated effort to take the curse off the prevailing sadism with a sprinkling of conventional pornography. The anonymous, ravenous Amazons who snack on each other in one obviously interpolated sequence are, I assume, Anneka di Lorenzo and Lori Wagner, ex-pinups cast (according to the press kit) as Messalina and Agrippina. They may also be the headliners in a later pas de deux around an erect penis, but frankly, the faces at the orgies become difficult to distinguish.

This unsavory fiasco began production in the summer of 1976 as "Gore Vidal's Caligula." Vidal began disowning it a year later and got his name out of the title, although one of the credits still reads "adapted from an original screenplay by Gore Vidal." Brass, credited with "principal photography," also disowned his work, although the lurid tone and stultifying atmosphere seem quite consistent with his previous feature, "Madam Kitty," sort of a poor man's version of Visconti's "The Damned."

Guccione now claims that Brass tried to sabotage him by making a disgusting spectacle for idological reasons. He also claims that Vidal will regret giving up 10 percent of the profits in exchange for having his name deleted from the title "now that 'Caligula' looks like it's going to make a fortune." While acknowledging that the film completed by Bass was "a mess," Guccione seems to be laboring under the delusion (or running the bluff) that the mess was cleaned up in the editing process. On the contrary, he's counting on sensation-seeking moviegoers to pay through the nose for the privilege of consuming repulsive merchandise.

Vidal tried to account for what went wrong in the course of a priceless interview that appeared in the April 1977 issue of American Film. In answer to a comment that production on "Gore Vidal's Caligula" had finished, he replied, "In every sense. One of the interesting things I have discovered as I proceed along the great road of life is that you make the same goddamned mistakes over and over and over again. I can tell you right now that every mistake you've made so far in your life you will continue to make. There's not a chance of getting out from under.

"Now I know quite a lot about movies. I know how they're put together. Yet I go from disaster to disaster. Obviously, I'm getting stupider. This time I have to get my name out of the title. I fear that Hugh Briss was back in town, as W.C. Fields would say. . .

"Bob Guccione of Penthouse -- the mag for the gynecological set -- is actually quite visual-minded and not entirely stupid; I thought that if the two of us had control of the picture, it would work. The script was strong, which is why we got O'Toole and John Gielgud and Malcolm McDowell and so on. Well, another disaster."

Indeed, the completed "Caligula" is such a mucky, distasteful melange of eroticism, brutality and pageantry that it's difficult to believe any script, let along a strong one, ever existed. The rise and fall of Caligula is never organized dramatically, a failing that is keenly apparent in the wake of the splendid BBC production of Robert Graves' "I, Claudius." Half an hour into "Caligula" you've abandoned any hope of dramatic interest or coherence emerging from such a debased, exhibitionistic context.

One of the more ludicrous moments finds Drusilla, played by Teresa Ann Savoy, insulting brother Caligula, played by Malcolm McDowell, with the epithet "You amateur!" and slaps her across the face. I don't know if Vidal actually wrote this scintillating exchange, but one could easily imagine the whole "Caligula" team running around shouting "Amateur!" at each other and trading slaps, followed by a triumphant "Take that!"

Even the opulent, lewdly preposterous sets disigned by Danilo Donati (who really splurges on prop phalluses) are handled amateurishly. The camera keeps receding to the equivalent of the second balcony so that all the set can get in the picture . It's as if Guccione wanted to make sure that he saw every single property he'd paid for.

Moviegoers who caught McDoell's demented Naze in "The Passage" should fine his Caligula pretty ho-hum, although it confirms his peculiar preference for degenerate leading roles. John Hurt's smugly hypocritical Caligula in "I, Claudius" was a far more disarming, menacing image of precocious despotism.

A familiar eminence identified in the press kit as "the indefatigable John Gielgud" seems to have a clear view of what's ahead. Cast as Nerva, a disgusted senator, Gielgud becomes a second-reel casualty, peacefully bleeding to death in his bath rather than serve a minute longer under Tiberius or his heir-apparent, Caligula.

Nerva spares himself a lot of grief.So will moviegoers who can resist inflicting "Caligula" on themselves.