I was lucky enough to have attended one of the live Tonight Show tapings they had in Orlando, and in between segments he was nothing but gracious and professional, interacting with the audience and expressing seemingly very genuine gratitude for the warm and enthusiastic reception they received from their Orlando guests and helping to make their show there a big success. I don't know if there's rumors that he's a jerk in "real life" or something, but if so he is at least professional enough and enough of a good actor to not let that show at all while he's off-camera.