Joan the Vampire Slayer
Carpe Spuffy!
I watched this episode earlier tonight, and now I think back on it Im starting to think it was brought out in them. Maybe from something thats so primordial from like caveman era and stuff that when Billy touches them brings it out. It obviously takes different times to truly show its affect, thats why with Wesley it sort of built up and then exploded. With some men it was pretty much instant. Its so hard to say really but it seems like that that force thats deep inside guys is just magnified by Billy's touch.
It makes sense that Angel isn't affect by it even though he said he lost all anger and hatred like that years ago its still there. I took it that because Angel is also demon technically that anger and hatred is already at the surface but shown in a different way. But then maybe because Angel has a soul it just doesn't do anything to him and maybe on vampires without a soul it makes them 10 times worse.
Gosh this is hard to pin point or come to some kind of logical conclusion. I guess its one of those things where you just have to take it as it comes when watching the episode.
Yeah, I used to think it was something that was done to them, but then when I watched the episode again, I changed my mind. I like your idea with how it would affect a vampire without a soul...scary thought.