Well, quite possibly, it could be some small clues here or there that are noticeable, most likely because the woman is doing her best to flirt and doesn't get that in return. I personally don't have that much 'real world experience' with many gays though. I live in a very rural area and have so for most of my life, but... here's an absolute riot of a story for you regarding this topic. My significant other, of 19 years now, had found a drinking partner, early on into our relationship and I could tell the guy was gay, or bi at least. My boyfriend kept saying that I was wrong and that something was wrong with me or that I was trying to stop him from having fun with friends and drinking. Until one night when he came running back to the house slammed the door, downed a glass of vodka and he looked like someone in shell shock. What happened, you may wonder? Well, hi friend pulled down his pants and proceeded to ask for a bj and to 'fool around', also I guess he was packing some heat. My boyfriend never saw it coming. ;)