''There's a total shortage of normal people,'' observes one member of Los Angeles' finest in this eye-popping documentary. We watch prostitution arrests along the Sunset Strip, see a female officer go all giddy at spotting Brad Pitt on the street, and are told by another cop, ''Everybody comes here: bad, good, horrible — the devil stops here sometimes to joke and smoke.'' The voice-over narration is unnecessarily melodramatic, and TLC is doing producer Paul Buller a disservice by showing the three one-hour segments of his documentary back-to-back. Still, it's gangs o' fun. A-