I think I am pretty normal, and I happen to think bi-guys are hot. It boils down to wanting what you can't have or maybe wanting to experience something new. As for women not finding bi-guys attractive, I believe that many women don't answer sexual questions truthfully. Many women are not honestly comfortable with their sexuality. So my answer is yes.
If you're into dicks (eww) and men -- i don't know why you can't just go one step further and like two men.
I've been shocked at how many women would kinda like another guy with their bf. If you press them -- the hidden truth comes out. Makes you wonder what they fantasize now when you're not around. Double ewwww!!!!