Okay, sideline anecdote over something that amused me.
Some years ago I was at a party and a couple of guys had been chatting with me on and off for a chunk of it, and then my girlfriend of the time arrived and I gave her the general hug and kiss. The two guys who had been amiably bantering with me paused, looked at each other and then did this whole.. "Oh, we've been flirting with you to see who could pick you up and you haven't acted offended or scared, so we really thought you were gay. Are you like, bi or just really secure in your masculinity?"
This was then spoiled when the gf did this "Oh no, he's polite, charming, a bit of a flirt in general when its for fun, but totally oblivious to people hitting on him in seriousness."