Auction dealer versus ???

A unit can go to auction for many reasons just like cars do.
There are dealer auctions were dealers take unwanted used units for auction. This can be because of age, quality of unit itself (dealer feels unit is to high end or low end for his lot) or it could be a repossessed unit. This is normal in the vehicle world and most cities have a dealer auction weekly.

You will be hard pressed to find any dealer that will give a warranty on any used unit (they will try to sell you a big markup after market warranty). This is were the predelivery inspection comes in. DO NOT GIVE THE DEALER any large chunk of money until after you do a predelivery inspection. Get everything in writing and insist on the dealer writing that your deposit is refundable should any major item be defective.
It is a long shot but ask the dealer if they will take the rig to a diesel shop of your choosing for checkout by a mechanic before purchase. Go to the shop and talk to them then YOU PAY THE SHOP for a thorough inspection of the powertrain and suspension. Ask them to write down the DOT dates on the tires any tire over 5 years old should be treated with great suspicion no matter how much tread is left on the tire. Probably cost you $150.00 - $200.00 but the upside is you will have a good place to take the rig for repairs/ maintenance after purchase.
Before purchasing from Camping World be aware many people think Camping World salesman are among the worst. DO a search or start another thread asking about the Camping World you are thinking of dealing with.
Personally I would never deal with Camping World as I believe them to be thieves the one time I dealt with them

Ditto above. Plus be aware weather dealer or private seller you have the obligation of knowing what your buying. BUYER BEWARE.
You have to live with after you own it no matter where it comes from.

When you buy a used rig, no matter the source, you don't have a clue how it was maintaind by prior owner/s unless you buy directly from the owner and can inspect all his maintenance records.

The best you can hope for is some type of sellers warranty for say 30-90 days.

Do a through inspection yourself, have it inspected profesionally, etc. then hope for the best.

Have fun with your new rig.