THE JERK -- At area theaters.

Television comedian Steve Martin's humor, in his first film, "The Jerk," is based on the juxtaposition of innocence and vulgarity. The premise isn't bad, but the ratio's dreadful. To point up a bit of engagingly comic naivete, the film is 95 percent disgusting.

Blatant disgustingness is not necessarily a handicap in film business, of course. But audiences should know that's what they're getting, and while the vulgarity is hogging the screen, there are few laughs. A woman in a Nazi uniform tries to beat up another woman. A crazed redneck curses and shoots at a stranger for the fun of it. A woman is tied to a stake and shot by a firing squad.

The joke is that Martin, a loving, trusting soul, and a ditto girl, played by Bernadette Peters, sail unharmed through this sordidness. They bob up and down on the seas of life, as it were, but never sink to the depths.

Well, all right. It starts off funny by Martin's saying that he grew up "as a poor black child," and showing him in the loving atmosphere of a sharecropping family, shocked to hear that he's adopted. There are two or three sweet moments after that -- the girl, overcome by romance on a moonlit beach, takes out her cornet and blasts a tune -- but nothing nearly as good. Just burps, crossed eyes and obscenities.