This summer someone dumped a pile of about a dozen steaks and meats by one of my water access spots. Was covered in flies and maggots and the whole area reeked for a month.
At another spot someone spray painted multiple boulders with big red "A" anarchy symbols. I'm gonna try taking some paint thinner and brushes up there to scrub it off on my next trip.
Some people are absolute scum. Guess the best we can do is not be one of them, and do our part cleaning up after them... but just once I'd love to catch them in the act.