Not necessarily. I have seen a lot of those too and many are very mismanaged trailer parks.
If you follow the usual steps in the MHU Due Diligence Manual you can find out the answer. Look up the data on bestplaces.net to vet the market and rental demand. Use a test ad to confirm the going rent rate and demand for the area. Look at comparable parks - are all of them really half full or just some of them? If you do these things you can find out if a park is mismanaged or if the area has problems.
I came close to purchasing a Park outside Kansas City and it had great demand, but it was a very big turnaround Park and the capital expenses it immediately needed could not be absorbed at the negotiated price. There was also a very limited contractor pool to perform rehabs, which I probably could have figured out over time, but initially it was a turn off.
Lots of threads on these steps doing some searches.