I see bits and pieces of me in all the characters in my films.
I think the more the actor lets you know what he thinks of the character, the less the audience cares - like a comedian who laughs at his own jokes.
But even with a character like Cary who is relatively outlandish, at the end of the movie he's in a place where I wouldn't have expected him to be - taking on the responsibility of a woman who is pregnant and who used to be his best friend's wife.