I'm fully incapable of growing reasonable facial hair. It grows in all.. patchy. It's thick around my chin, then it gets all sparse on my cheek/jaw, and sorta re-thickens near my ears. When I let it grow out it looks all white-trashy. So clean-shaven for me.
Plus, I have to say that I have a rather nice jaw. Facial hair would only serve to obscure it.
PS: I'm only 20, so in a few years I'll probably be able to grow real facial hair. My dad couldn't grow anything legitimate until he was 23 and now he has your typical middle-aged man goatee. Looks pretty good on him too.