I'm bi but don't "look bi" to homophobes and I've never heard someone more obsessed with gay stuff. I honestly think a big part of it is they see very feminine gay guys as the "only" gay people and that's not who they see in the mirror so they couldn't possibly be gay. Yet their ass is the one constantly thinking about it, mix that with good old religious guilt tripping about a natural mammalian trait and you have angry guilt ridden repressed gay/bi people that are angry that people are just allowed to live a life that they feel they can't.