KOA's are no worse than any other CG. THere rates are generally a bit more but you pay for the advertising and familiarity.
In general you know what your getting with a KOA in terms of cleanliness and overall operation vs. mom and dads RV park.
Generally KOA will be fine for an overnight.
You won't find a lot of permanents, the bathrooms will be decent, the sites will be accessible. There will be a stocked camp store. You can count on KOA providing your basic camping needs vs. Bill's roadside camp resort.
Yes KOA is more expensive by comparison, but KOA will be at the top of the heap in terms of necessities.
You can pay a little more for a known quantity or you can take the savings and roll the dice on an unknown RV park.
There was a time when I avoided the KOA but experience and a few run down parks have taught me to go with an established known quantity vs. looking for a bargain.
I frequent a few bargain CG's that I enjoy. However in the mid Atlantic the bargain CG's are in remote areas vs. being prime time and close to the interstate.
When traveling through if you find a bargain CG close to the interstate, beware it maybe more than you bargained for.
When comes to rates and price increases KOA is not the leader.
A few very popular resort area CG's that know have raised their rates $50-$60 per night. It used to be rare to find a $100+ cg in my area. Now there are a few.
I have opted to do a little more state park and COE camping vs. paying the higher rates. Although I still prefer the prime CG located close to the attraction vs. the bargain CG a few miles away.
I seldom stay at KOA's however I would not avoid them solely on price. If they are the best and most convenient CG to meet my needs I have no problem staying there vs. traveling farther to save a buck at a questionable CG.