"Among some comics 'Late Show' has a reputation for favoring a certain profile. 'The types they seem to like are middle-aged white men from the Midwest,' the comic Amy Schumer said. Only one woman (Karen Rontowski) was booked in 2011. 'There are a lot less female comics who are authentic,' Mr. Brill said. 'I see a lot of female comics who to please an audience will act like men.'"
But this is probably what got him canned:
"But there are also questions about conflicts of interest, particularly since only 22 comics, including Bill Cosby, Jerry Seinfeld and less famous performers, were lucky enough to get segments last year, and comedians presumably take his classes hoping for an edge in getting on the show. 'He trades on the name of the show,' the young comic Anthony Jeselnik said. 'He has workshops, a festival. He has the market cornered. I can’t believe Letterman lets him do it.'"