back biters and vicious gossipers. you know people who have nothing better to do than scorn others behind their back, make rude innuendos and are just all around nasty.
Seriously, targeting and saying nasty things about someone doesn't make you a good person, especially if you (proverbial you) is too much of a coward to say it to the person's face. I have a friend going through that right now.
It doesn't bother me so much (though it can hurt) when someone does it tot me, but it really upsets me when someone does it to someone I care about. It is even worse when the people doing something so petty like that are in a position of authority.