I've found, as a straight man, that gay men are pulled like magnets towards me. I guess I'm sort of a traditional straight man and that's probably noticeable to someone who's gay, much like you can tell with some that they're gay.
I don't mind gay men around me or anything like that, but it can get a little uncomfortable when they say "I want to suck your dick" "I can do it better than any girl" and when asked to stop, they don't. I'm not generalizing at all, but it's what I've experienced with more than a few people.
I'm not homophobic, I'd react much the same with a woman I find unattractive but some gay men have been very pushy. When I was young I worked with an older gay man and he did this all the time to the point I got fed up with it.