So far, I've been lucky with campsites so far. Most people tend to have music, but it isn't ear-splittingly loud.
If I did encounter a CG that wouldn't do anything about someone's music so loud that it drowns out my RV inside my rig, I'll pull out my dB meter, take pictures of it at various places, hitch up, and head to greener territory. I've yet to post a negative review (I always leave a positive review at every CG I go to because I feel like a lack of negative items is a BIG positive) or contest a credit card, but those are always options that can be used.