Beginning as a stinging, double-edged satire of stereotype exploitation, Spike Lee's racially charged "Bamboozled" slowly turns into a heavy-handed horsewhipping as it loses its sense of humor.

Intelligent, persuasive, scathing and certainly provocative, the picture is a pasting of upstart TV networks that pack their schedules with clownish urban sitcoms to build a woop-wooping, lowbrow fan base. With this film, Lee is asking just how far such degradation must go before it's recognized as being socially detrimental.

Damon Wayans (no stranger to blaxploitation TV) stars as Pierre Delacroix, an ostentatious, Harvard-educated "oreo" who writes for a WB-like network. Fed up with reprimands for writing "too white," he pitches a concept so offensive he hopes it will both prove a point and get him fired from this job he can no longer stomach.

His idea: A Vaudevillian minstrel show featuring black performers in blackface, resurrecting every appalling stereotype he can imagine. He recruits two hungry street performers (played by comedian Tommy Davidson and dreadlocked tap-dance virtuoso Savion Glover) to star in the show, which will be about "two real coons" who are "ignorant, stupid and lazy." They'll live in a watermelon patch on a plantation. The characters will have names like Sleep 'n' Eat, Honeycut, Topsy and Sambo. The house band will be called the Alabama Porch Monkeys.

To Delacroix's dismay and utter disgust, his I'm-so-ghetto white-boy boss (Michael Rapaport) loves the idea, declaring "I'm diggin' this, yo! This could be bigger than Amos and Andy!"

Nobody ever accused Spike Lee of being subtle.

The first half of "Bamboozled" is both darkly comical and potently contemplative about the social consequences of perpetuating the kind of racial profiles Lee accuses many ethnic sitcoms of espousing.

Lee takes us backstage at the new show with scenes of the actors applying pitch black makeup (made from burnt cork as it was in Al Jolson's time) to their guilt-ridden faces, and watches them become buffoons in front of a complacent studio audience that before long is a sea of woofing fans in blackface and white gloves themselves.

(The director also takes aim at advertisers who exploit the ghetto image, showing mock advertisements for Da Bomb malt liquor -- a two-liter bottle of booze shaped like a missile -- and a clothing brand called Tommy Hillnigger Jeans.)

As the minstrel show takes off in the ratings, its pompous creator begins to believe his own hype. The impact of this transition is partially lost, however, in Wayans' deliberately hyperbolic performance as a mock intellectual ashamed of his black heritage. Spouting words like "pray tell" and "Negro" (never "black" or "African American") in a snively, upper-crust accent while tapping his fingertips together like a stern father, he soon becomes so grating that the irony of his hypocrisy is overwhelmed by sheer annoyance.

Meanwhile Davidson and Glover, who at first go along with their debasement to put food on the table, soon convince themselves they're part of something daring and groundbreaking too. As a result their egos explode. In "Bamboozled" all the main characters betray their own ideology at some point.

As a screenwriter, Lee delivers a sharply observant and ultimately effective piece of shock therapy. But as a director, he gets carried away with making sure his message gets across. He opens the picture with voice-over definitions of the words "satire" and "irony," as if he considers his audience too thick to understand the film without having his intentions spelled out for them. He has trouble maintaining the balance between parody and pulpit. By the halfway mark, the din of self-righteousness begins to drown out much of the movie's stinging wit.

Once Lee has climbed onto his soapbox, he begins baiting viewers by taking pot shots at racial and historical ignorance within the black community. He implies certain black celebrities are Uncle Toms. Then he introduces a group of rappers/terrorists who write indignant songs about revolution even though they haven't a clue what they're rebelling against. Part of a movement that rises up against the minstrel show, they help bring the story to a violent end -- a development that feels too much like a black stereotype itself.

"Bamboozled" isn't completely ruined by Lee's evaporating sense of satire. The dizzying array of historical footage edited into the film showing blacks exploited in showbiz certainly helps make his point, as does the extensive collection of racist antique knickknacks Delacroix accumulates in his office as the minstrel show takes over his life and his arrogance becomes self-loathing.

But the movie's equilibrium is all out of whack because as a writer and a director Lee can't seem to stick to parody and let the material speak for itself.