Then it reminded me from my parenting books that you shouldn't tell your kids that they are bad, you should tell them they are acting bad. Seems stupid right? Or at least pointless at first. But if you think about it in the first scenario there is nothing they can do about it, they are bad, in the second scenario they just need to act good going forward, easy peasy. They can still feel good about themselves and strive to be better. If they are bad then, screw it, might as well be bad.
This works for talking to adults as well, for you and them. Rather than really hate someone for being a terrible person, just realize that they are acting terrible and can change. Try to figure out their motivations and look for ways you can change the situation so they don't act so terrible. I think it's called negotiating.