Motorhomes are not like cars. Most people don’t put a lot of miles on them. It could be either they didn’t use it much or they lived in it fulltime and stayed put (this can usually be determined by the interior condition). I probably put less than 1000 miles a year on mine anymore but I do start it once a month and run it through the gears and pump the breaks a few times and run the AC. I would do my usual through look over as I would any vehicle no matter what the mileage is. Spend a little time looking at things, engine, trans, tires, under and over the whole unit. Even if you don’t know what you are looking at you can still usually spot things if it doesn’t look right.