Actually you have more problems with a new coach then a used coach. New coaches usually have to have several things adjusted. Owners are usually looking for stuff on a new coach to get fixed before the warranty runs out. Once you get those new bugs out, you usually will not have many problems.
I know for a fact on my coach the problems that needed attention were when it was brand new. I had a leveler that had a small leak, so I complained about it and they replaced it under warranty. Had a Huei pump that failed on the engine which was replace also under warranty.
But other then that I have not had a single issue in the last nine years. And I keep on reading in this forum about problems with coaches, and it seems most are on brand new coaches. Problems with slides, the problem Cummins had with their wrist pins failing were on brand new engines. The problem with Cat engines when over filled with too much oil dumping it out through the breather tube getting on the radiator on some coaches that did not have the extended tube. But once all these corrections were made when new, you hardly hear of these problems later on.
So Yea! I have to agree that sometimes it is best to buy a coach that has gone through the breaking in period.