Our first two we've bought new. The first one was a 4 year old 24' Rockwood from a Pleasureland Dealer. I'm a mechanical person as a farmer but we didn't know a lot about campers at the time. We got a excellent salesman who was very thorough. He showed us how everything worked and glanced over things that a person should look at on used ones. We didn't have a single problem with it in a year and a half but outgrew it quickly.
Our second was a less then one year old Sundance XLT in our signature. It on the other hand had a major issue we didn't know about at the time. Getting ready for our first trip it tried to start on fire in the junction box were the flexible pull out cord connected to the hardwire cord. We got it fixed correctly and figured out the AC, microwave, and fridge had all been replaced since new which were guessing is why the people had sold it so quickly. It would have been a hard one to catch in a PDI. It was a cheap fix of less then $50 in wires and appropriate wire connectors. For the money we saved both times I'd do it again but I've learned a lot since and know more what to look for.