I think the MFA programs have had a real effect on the state of American fiction, but I don't think it's a question of "this is written by someone with an MFA, and this isn't." I challenge anyone to identify a book in that way. It's totally impossible.
Chad HarbachLooking at and shaping your own work is a very intuitive process. You see something you've written in your notebook. It's there on the page and either feels right or it doesn't, and it's hard sometimes to go beyond that and discover why it feels that way.
Chad Harbach