In my experience, it's very rare that a guy will come up to you outright and say he's interested. Usually (especially among the gheys), it's a bit more subtle. Is there a particular kind of eye contact that clues you in? Body language? Touch?
He tends to start acting a bit "protective " over you. Not possessive tho just sort of protective and compliments u quite often (more then 3 times means he is into u but just to shy to say it straight up so he hints at it by complimenting you hoping you get it lol) those are some of the obvious ones that I've experienced lol
Watch for the eyes and if they make special effort to contact you, they might be interested. There's no surefire way unless they say they're interested though.
He will show interest in you like favoring your comments or tweets, message you back, or try to hangout with you, but if he doesn't display any interest in you don't grow any false hopes.
