There are two primary pitfalls in making movies about drug addiction. First: the subject matter has already been covered, beginning in the '50s with "The Man With the Golden Arm," so the audience knows the protagonist will inevitably collapse. Since then, the real-life dramas of Janis Joplin and John Belushi have already been explored and exploited. Second: if the story proceeds through rehabilitation, there's the challenge of not being preachy. "Clean and Sober" (1988) is one of the few films that avoided this. Writer/director David Veloz's "Permanent Midnight" falls into both pitfalls - and worse - as it chronicles TV comedy writer Jerry Stahl's real-life recovery from heroin addiction in the form of a confessional, filled with flashbacks. Stahl was one of the writers for "Alf" and other sit-coms. Ben Stiller, who has made a career out of playing nice guys who are losers, plays Stahl. He's graphically shown shooting himself up with smack, complete with blue-hued skin, blackened eyes and drops of blood squirting onto the bathroom ceiling. He behaves like an idiot and epitomizes decadence. Once he gets into rehab, of course, this predictably changes. Problem is: he's miscast and it's all very episodic and ultimately boring. British model/actress Elizabeth Hurley appears briefly as his ambitious wife-in-name-only, the result of a green-card marriage, as do Cheryl Ladd, as a TV star who recognizes his problem, and Janeane Garofalo as an inquisitive agent. On the Granger Movie Gauge of 1 to 10, "Permanent Midnight" is a sordid, junkie 3. Just say no.