Rv park reviews.com may be of use. Some people, including me, include a mention when a campground is mostly permanent residents if it makes the park less desirable (not necessarily the case.)
I have no gripe with seasonal residents most of the time and certainly understand why park owners rent long term to permanents. But I've stayed in parks where there was junk littering all over the place outside every unit, where the washing machines were filthy from oil field worker's clothes, and where the guy in the site across from us had large, loud industrial trucks coming and going 24/7. Those were parks charging $30+ per night so not necessarily cheap joints.