Im bisexual. Im not of the blindly blushing run for a pair of breasts or testicles. For me it is a matter of personality rather than gender or sexual orientation.
Like for example... it doesn't matter if a girl is straight or lesbian, cause if she's a stupid blond bitch that would constantly nag and complain then I throw her out the window either way (or jump out of it myself if the girl would be too heavy).
It also doesn't matter to me if a guy is gay or not... He can listen to whatever he wants, hip-hop, rap, trance, rave, but if it's loud and my ears bleed then either way he gets a kick in the ass and flew through the window as well.
Those are just a few examples... (wow and I avoided mentioning sex, makes me feel less like a pervert) of reasons why i wouldnt like a roommate in particular, but yes as said, it's the person and attitude that counts and not the gender/sexuality.