Tbh, unless a guy is a fem or queen, it's much harder to tell if he's gay from a distance (no conversation, just observing).
The one thing that seems to never fail however is eye-contact. If you're lucky and a guy finds you attractive, you'll catch him looking at you, and when/if you make eye-contact they'll usually stare longer than they "should", even if they don't want to be noticed. Also, after eye-contact is broken, they'll look again your way fairly quick.
Basically, follow his eyes. Even if he's not looking at you, see if he's constantly eyeing men more than women, and if so, you've got a GHEY.
The great thing about this method is that people tend to look at what interest them, but on a subconscious level, so you can spot the (sometimes closeted) masculine one's who are trying to live a lie...and set them free.
