I don't think that there's a hard number anywhere that you can say "this will be good, that will be terrible", and you can always have good or bad luck. I've noticed the littering too, maybe that's an indicator -- but in the end, it could be one person doing the littering, so it's probably not super reliable.

The dollar value is hard to estimate. I'd pay a few hundred extra to only have neighborly neighbors, but I probably wouldn't if my budget was tighter. Would I pay 2x or 3x the price? It depends. When my one neighbor was escalating hard, I totally would've, but when he's mostly normal? Probably not.