On a recent long (7 state), trip we encountered lots of Good Sam "RV Parks" that were nothing more than run down trailer parks with a few transient slots. I can only assume no one from GS ever bothers to actually go to these parks before selling them their GS badges.
Most of the park model parks described by the OP are actually in better shape than many of those we came across. On more than one occasion we drove through the "Park" and drove right back out again as we were not even close to being comfortable staying there even for just a single night.
While we prefer actual campgrounds about once a week we want the additional amenities found in a real RV park - Wifi, laundry facilities, the ability to drop our tanks etc. and we pay the extra for them.... but when we hear the Banjo's we press on. :E