I have a very very short "shit list". I'm tolerant of a lot of things, but people who have humongous egos and have no problem hurting and blaming others just so they feel propped up, they go on that list. People with no personal integrity or concern for others. I have given people like this a LONG time to see the error of their ways, because I find it astounding that anyone can be so selfish or self-deluded,... but eventually there's a big thing that happens and that becomes a breaking point.
My "list" essentially just means I stop talking to you, and may complain about you for a while (but not nearly as much as that person does about me, apparently). Now I can spot these types immediately and I know not to waste my time with them.
I think I have just... 2 people? And one I just sort of pity for her own ignorance. My Thinking side overtakes my Feeling side typically when it comes to things like grudges.