No because sometimes being brutally honest to someone about their bad points or qualities is the best way to "hit home" and maybe stop this person from being so mean or nasty to other people.
It sno wrong if she or he is your true friend and your honesty is coming from a place of love but if you don't like them they are not your friend unless two faced and say you like them when you don't and thats as wrong as you can get but if you don't like someone and your brutally honest than its called rudeness and the problem with brutal honesty is some people don't agree with the fact that it is honesty some people may think it lies so unless your being brutally honset with a very very close friend I wouldnt do it
Because it might make them feel bad O_O
Sounds like a nice way of taking revenge , keep it up