Always a Risk
Whether you are looking at Ebay, Craigslist, RV Trader or whether it is being sold by a dealer or private party there is always a risk. I have purchased two class A motor homes on Ebay. I have looked an numerous from dealers and private parties.
Gauge what you can afford. The lower cost 18-22 year old units are more likely to have issues, but also cost much less. Keep in mind many creditors only finance 10-12 years out. A few will go as far as 18 but usually you have to have great credit. Likely if you need to purchase on credit you will need a home equity or signature line of credit or plan to have cash.
Regardless of where it is listed an honest person/business will give an honest ad. Most likely if someone is trying to cover something up they will simply leave it out of the ad all together. After all non-disclosure makes them honest and reputable.
It is always buyer beware so when you can go look do so. I drove 700 miles in two days to look at 7 motor homes. The ones from the dealers lots that I looked at were the ones that had the most undisclosed issues.
Often ads will present the fluff in purchasing the motor home but leave out the real important things. Private owners may overlook things out of ignorance, dealers should know what is important.
A few pointers:
Low miles in a car is good, low miles in a motor home may not be. If you have a 20 year old motor home with 20,000 miles that means it could have been lived in or maybe used once a year. A motor home sitting that long may have issues that even the owner is not aware of. Don't not purchase a motor home with low miles but be on the look out for problems.
The roof is often never mentioned in ads. Leaks are one of the biggest issues in older units. Someone being upfront and honest will mention the roof, condition and also show a photo of the roof. If not, be sure and ask if you will be buying something you will not see.
Fluff like TV's, Satellite antennae etc are great additions, but don't make your purchase cause of these items. The engine, transmission, functionality etc are what is going to cost you big bucks if something breaks.
Most ads will list a generator, but should mention its starts easy even cold. It should always brand and hopefully size, hours and fuel type. Size is important as if you have two roof air conditioners a 4,000 is probably not big enough. If the generator runs on LP then the size of the LP tank is more important. If you are always going to be in parks with service this may not be as important.
Number of air conditioners becomes more important in warmer areas and in bigger RV's
NADA is not always a good comparison for motor homes. It is age, condition and what the market is for similar units.
The one I just bought was from a private party and they listed every primary item or feature, stated operation or if they did not know they stated that and they also indicated any service they had done and approximately how long either in time or miles. Makes you feel much better about your purchase.
If you are driving a large motor home for the first time be aware that the rear tires are the pivot point of the turn and there may be 10 or more feet swinging behind them.
Hope this helps someone.