Nice people can pick up harmful attitudes and do cruel things. Many of my friends aren't vegan. Lots are speciesist. Quite a few are pro-breeding. They're still nice people. They just don't act it in some ways
Hitler's a great example, because most people love picking on him. He loved his friends, adored his neice (iirc), educated people on the dangers of smoking because he didn't want them to suffer and die unnecessarily from doing that, and according to a friend who watched a documentary about him that came from a secretary who worked for him the last few years until the end: he treated his workers very well, he even forced them to leave when Berlin was being bombed and they didn't want to go; he was very nice to his wife; he was way way too nice to his dog. Now that's disgressing.
I do hope the guy coughs up the money. You could also check the laws in your area, see if they apply to your case, like leaving you with his sick pig to deal with without giving you resources and guidelines for handling vet care, abandoning his animals.
Would dirtying his doorstep make it so much worse for the rest of the city? It would just sux if you got caught.