He's apparently stolen some jokes, which is about as bad a thing as you could possibly do in the world of comedy.

He has a record of treating other comics in LA clubs very poorly. He ignores stage time limitations, takes other peoples' time unnanounced and without apology, etc. This is pretty much the second worst thing you can do in the world of comedy.

He's also the kind of comic who acts like he's being outrageous when he isn't. And the kind of comic who turns non-jokes into jokes by acting like an ass.

He also sucks off his fans by telling them how wonderful they are for liking him.

Also, his success has been wildly disproportionate to his talent, because of his looks and his focus on self-promotion and marketing.