Buying used from a dealer

I would be very careful buying anything used from a dealer without a through inspection and documentation. We are currently shopping for a motorhome to replace out TT and are finding that virtually all used units come from auctions. While there is nothing wrong with an auction purchase you have no history available from the previous owner and no factory backing. While the markup profits are likely less than with a MH, I'm sure a tidy profit can be made in the used TT market. I just read a lengthy post from an individual who got "burned" on a used 5er. So look carefully at used units and ask a lot of questions about how they obtained it.