At least that is the cliche, and one that most stand-up comics I have known of would atest to. Why is this? Is it just something that is exagerated by them so that they then seem to deviate so radically from the norm? Or are most stand-up comics really bi-polar, suicidal, alcoholic drug addicts that hate their parents and have a desperate need for attention?
Could be. I’d guess it’s not at all unusual for people from dysfunctional families to develop a sense of humor as a coping mechanism.
Perhaps the real question is “Why do so many f’ed-up people become stand-up comics?” 
I don’t think it’s an exaggeration, or ‘character,’ at least not for most comics. As a35362 said, humour is a coping mechanism; it can also mask anger/aggression. Though some comics mask their anger better than others… {grin}
Ugh…you just reminded me of why I hate Lewis Black.
I’d tend to agree with the premise that some of these people use humor as a coping mechanism. On the whole, comics are not usually very funny off-stage. Sometimes they’re downright mean and nasty (Milton Berle and Desi Arnaz and Harvey Korman come to mind). Yet they go out there and are so freakin’ funny they put you on the floor. Weird…
It may also be that it takes a F’d up person to stay with that line of work.
Stand-up comedians lead a very crappy lifestyle until they get lucky and break in big time.
They are on the road a lot traveling from city to city living in motels which doesn’t allow them to ever settle down and start a family or buy a house. Most of them are single.
They are also free-lancing and have no permanent employer so benefits like retirement savings or health insurance are non-exsistant.
They have no job security and rely on constantly getting gigs somewhere.
For someone to do that as a full-time job is a little f’d up to begin with.
Have you guys seen Comedian, the 2002 documentary about stand-up comedy featuring Jerry Seinfeld and Greg Geraldo? I thought it was a very cool behind-the-scenes look at that world.
No, some of them actually have problems!
[rimshot]
THANK YOU!
I’ll be playing the big room all week!
It sure does seem that they’re trying to compensate for something, doesn’t it?
For another data point, did you hear Terry Gross’ interview with Rodney Dangerfield last night on Fresh Air? You can listen here. Its the last 20 minutes or so of the program. There’s a link to the Rodney interview down the page.
In brief, he had a horrible childhood. His father had left his mother to raise him alone, and his mother was a selfish biatch. He saw his father for two hours every year. He never had any pleasures as a child that we take for granted, like going to ball games or amusement parks.
And it hasn’t gotten any better. Over the past few years, he’s suffered heart attacks, and arterial bypass surgery for both his heart and his brain. (Yes, when I read the headline “Dangerfield has Brain Bypass,” I thought it was a joke, too.)
I’ve never heard him talk about his life before. On all of his Tonight Show appearances, he was always “on stage,” and never anything but funny. It’s pretty poignant.
And he sounds horrible.
Glad you mentioned Rodney, bughunter; he leapt to my mind as well in the department of Comedians with F’ed Up Lives. I just finished reading his autobiography (of which I have an autographed copy), and it confirms much of this. It’s also filthy and hilarious, btw.