If it's someone I don't know or a cool person I wouldn't. If it is someone I know to be a douche, or say a player who had at an earlier time just rolled up on a ??? my group was working with, and spammed trade w/o even bothering to make an attempt to negotiate rotating pops... well then I would declare a Holy war, and annihilate them! Also killing your friends when they get charmed produces hours of family fun.