I loved Socialism's post, that would be an awesome thing to do, even if you don't have a decked out PvP character, they would probably be to chicken to call you on it because if they really wanted to PK you without the use of hacks, they would.
Anyways, best way to avoid it is making friends and playing private, just be careful like Manago said of friends of friends, if you don't quest with them alot, just stay back, leech, be a walking aura, curse thrower whatever it takes, but watch out.
I know Blizzard wont reset the ladder anytime soon, but they need to run warden better, I'm tired of hearing about MH'ers getting away with it and also all these dumb pricks using hacks.