I don't Pass even fully dressed, not even at a distance in bad light. If some guy gets up close enough to sit near me and still can't decide what my face suggests more, then the guy is too drunk to want anything to deal with anyhow, and said drunk doesn't get straight answers out of me about my gender.
A guy who is not drunk is probably pretty sure I was born male. If he asks anyhow, to be sure, he gets an answer, and I then proceed to bore him about how hard it is to find clothes and so on. It usually doesn't take long for the message to get through that I'm not there to be picked up.
I don't flirt with the guys; I don't know how to flirt with anyone. The only person I know of who is worse at flirting than I am, is my wife.