used RV - carfax shows driven 50,000 miles in one year

Sounds like emotions are driving your desire to buy it.

If you are not planning on putting many miles on it or if it is at the top of your purchase price, then
get the mechanic of your choice to go thru it.

If you are planning on driving it much, I would be concerned with repairs and resale value.
As this is the time of year to buy RVs cheap and many are for sale, I think I might keep looking. Don't know about your area but many are around here without high miles.