I haven't run into any real bad campsites but have seen a few where people tried to burn garbage/TP in the firepit and it didn't work.

Other trip reports have reported some nasty sites.
I go early spring, so it's not a problem then or mid-Sept which could be?

Being solo I make a point of trying NOT to stay at those 5 star sites unless they're just too good to pass up.

Sadly you'll find PIGS anywhere but getting a little off the most popular routes/campsites will lessen that possibility considerably IMHO.