Didn't Punker Barbie already touch on this?
It turns lots of us on when a guy is confident enough in his own sexuality and eager enough to please that he will put on a show for us with another guy.
I don't have any one set of criteria for guys turning me on, but one thing that always excites me (physically, emotionally, etc.) is a guy who is enthusiastic. Not like a cheerleader, but someone who allows himself to feel and express joy, delight, awe, excitement, happiness, curiosity, etc. Someone who is in the moment and responds to positive stuff, instead of just being a bitchy sarcastic negative "macho" dick. Guys who will sing along with stupid songs on the radio, laugh really hard, etc.