I've never had much of a problem with trash or riff-raff. Some stuff does get dumped - I did have to dispose of 20 tires when I bought my last piece of land, which sucks. I do occasionally find a drink cup or water bottles (they're the worst) - hunters are pretty good ATV riders usually even better, "nature hikers" are absolutely the worst at leaving trash (danged hippies), and dirtbikers never litter. I hate hikers. Anyway, yes, I do have to police a small amount of other peoples trash, but that's just part of my service to society. Honestly though, I think I would have a bigger problem with that if my land was posted. More and more people do appreciate us "open use" landowners these days. Except those danged pretentious hikers, of course.
JayC