As any male knows, only your mates assign you a sexual orientation, based on their perception, your alleged behaviour and, occasionally, your protestations. Women, in contrast, will always be women but men are only socially labelled "real men" after a passing muster with other men. Professing an interest in other males or any kind of "deviant" (i.e. all non-hetero) sexuality will guarantee you the label queer, no matter how many women you sleep with or insist your "deviancy" is out of curiosity rather than taste, or, worse, orientation.
This is a longstanding given in male social history. The ancient Greeks were not "bisexual" but actively interested in fucking epheboi, adolescents in the first bloom of adulthood. They would have scoffed at the notions of our modern gay sexual orientation definitions. Even the label bisexual would have been laughed at as dishonourable for men - if it meant taking the passive female position in sexual intercourse.
This is why in the current fashionable vogue of "bi-curiousness" or bisexual claims by many a straight man isn't really all what it seems. When I meet those guys in a sex club, they are there - dusty boots and check shirts included, straight from the building site - not to get some sweet loving from a male because the girlfriend is unavailable, nor to try out being anally penetrated - you'll get a slap if you suggested it to them - but to get a good blowjob, because they have heard we give them better than their girlfriends.
So I think labelling males who seek out other males to perform sexual services on them they normally expect and get from their girlfriends as bisexual a tad misleading. And they wouldn't describe themselves as such either: recall the many interviews with male hustlers who only take an active role - they never regard themselves as gay.
Top and bottom roles, as this is familiarly known in the gayworld, matter more to the sexual self-definition of the exploring straight male, than labels such as gay, bisexual or queer.
Mark relates an episode from his own sex life - something he does not do enough of, it's all theoretical bones without some hot muscle!:
A separated ‘bi-curious’ fireman in rural England I met a few times before he went back to his wife recently contacted me to tell me something rather alarming. ‘She found out about you,’ he said. ‘She hacked into my Hotmail account.’ ‘Oh, shit,’ I said. ‘What did she do? Did she throw you out?’But Mark leaves out the most crucial bit of information that would support my argument (or not): did he top or bottom before he went back to his wife? We should be informed! Real bisexuals take it up the arse like a man before they go back to their girlfriend. All the rest is "bi-curious" cant.
‘No,’ he said. ‘She got turned on! She wants to watch.’ The poor guy had to tell her that that this really was a kinky bridge too far for him. That he was too much a traditionalist to go down that path...