How do YOU tell when someone is gay?

I never think someone is gay. I would LITERALLY have to walk in on them having gay sex, have them stop and say, "This is EXACTLY what it looks like," and have the other person confirm this before I'd think, "Hey, maybe Ted's gay..."

SIMPLIEST METHOD:

Track their eye movements carefully. Everybody's eyes wander when they're not used to focus. So during a casual coffee or lunch, notices where his/her eyes gravitate towards. This works best if there are attractive people around for them to glace.

When they don't show any real interest in the opposite sex, I guess. When most of their lovers are the same-sex.

When I kiss them on the lips

Some pretty good signs here... liar, dishonest, theft, two faced, involved with drugs, backstabbing, to name a few.

When they wear extremely long V-necks.

it's not infallible, but you usually get a sense if you hang out with someone

Their voice and they way they act and dress.

http://www.youtube.com/watch?v=nw7IMYl5oU8 watch this and everything will become clear

when they have sex with guys...