SERIAL MOM *** (for John Waters fans).

H.L. Mencken, the Sage of Baltimore, declared that "No one ever went broke underestimating the taste of the American public." Oddly, while this maxim applies to practically everything, it does not quite fit Mencken's fellow-Baltimorean John Waters. Readers will understand what I mean if they know Waters' "oeuvre": the 1970s' shoestring underground works like "Mondo Trasho," "Multiple Maniacs,""Pink Flamingos" ; the more commercial 1980s' films "Polyester" and "Hairspray"; the 1990 "Cry-Baby."

Waters operates on the principle of going over the top, of exploiting kitschy , campy tackiness in weird, gross yet affectionate ways. This strategy has placed Waters movies beyond the reach of ordinary "bad taste" criticism. And even though Waters has gradually watered down his shock effects, he remains the high priest of a unique kind of filmmaking.

"Serial Mom" obviously feeds on the idealized families that young Waters watched on TV in the 1950s. His Sutphins are sweet Mom Beverly Sutphin (Kathleen Turner), nice dentist Pop Eugene (Sam Waterston), and -- note the cute, sitcom names -- boy-crazy Misty and son Chip. Chip works in a video store and shares with his friends a passion for horror flicks, the gorier the better.

The Sutphin home is the kind of orderly "Ladies' Home Journal" place that may remind you of the romantic opening of David Lynch's "Blue Velvet." Mom, a maniac for neatness, wears a perpetual smile -- but watch out when she spots something amiss in Eden! Her face clouds over. She stalks an offending fly and smashes it dead in the title credits. " Directed by John Waters" appears over the splattered insect. The end credits state that "no flies were hurt during the making of the movie."

Although Mom looks normal most of the time we quickly realize that she takes umbrage at a lot of things. Like chewing gum , dirty language (she refers to dog doo as "the brown word") or bad manners.

When Mom disapproves, Mom gets nasty. Not bitchy-nasty but killing-nasty. A friend who steals her parking place becomes the object of obscene phone calls. A neighbor who won't recycle is declared fit to be killed. The date who stood up daughter Misty gets terminal treatment in which "de-livered" acquires a new meaning. Juror Number 8 (an attractive Patty Hearst) disturbs Mom for daring to wear white shoes after Labor Day.

An elderly lady who refuses to rewind the videos she rents from Chip is attacked with a frozen leg of lamb, something no doubt seen by Waters in "Alfred Hitchcok Presents," and which itself came from a Roald Dahl "The New Yorker" story. Unlike Hitchcock however there is no mystery or true suspense. Mom keeps leaving obvious clues yet still gets away with crime, thanks to police ineptness and her family's brainlessness.

When finally the cops stalk Mom, they do it with the longest line of police cars since "The Sugarland Express." And when she goes on trial and acts as her own lawyer, she outfoxes judge, witnesses and jurors in some of the funniest moments of the film.

There's much else happening in the film, including violence as an aphrodisiac. It is all consistent with the title's word-play. Kathleen Turner does to a turn a Cereal Mom who becomes a Serial Mom, while --and that's the film's originality - still remaining a Cereal Mom. She's no Jekyll-and-Hyde, alternating personality but a whole with co-existing halves.

"Serial Mom" skips some of the more vivid sights (and instances of coprophagy) of vintage Waters, though there's raunchiness and gore. But as this is no black humor movie, as the continuity and logic are incredible and outrageous, the would-be macabre becomes a cartoonish fantasy. Gore is defused. How much? It depends on the viewer.

On this send-up of 1950s life-as-lived-on-TV, Waters places a 1990s overlay. He mocks our obsession with media personalities and our heroicizing them, no matter who they are. He contrasts violence with bourgeois values and fixations on what passes for beauty: Franklin Mint collectibles come in for a big share of ironies. Mom, on trial, parodies Sharon Stone, Joan Rivers on "real" TV interviews women who love mass killers, and Suzanne Somers flounces as the star who will play Mom. The film has many emblems of our ridiculous bad taste.

All this isn't exactly profound. Waters' excesses within a one-gag plot do not dig below the surface. Unlike Fellini who integrated his grotesqueries into a much larger context, Waters essentially mocks idiocies that we are all familiar with.. The result is a movie that, while not constantly funny, entertains a lot, has a brisk pace and , so to speak, no dead spots.