I bought a 15 year old Safari Trek last year, while not a diesel, it is a quality built rv (full body paint, Aluminum roof, solid wood cabinets, etc.) Since then I have put about 6,500 miles on it, and so far I can list number of "house" side problems on 1 hand:
1, the low point drain valve has started to drip when the system is pressurized (leaks 1-2 gallons per day)
2, I have a clip on plastic light fixture cover that is prone to falling off, I keep finding it on the floor.
3, I had an 18x18 inch mirror on the wall fall off a couple of weeks ago (factory adhesive gave out)
The previous owner installed new carpet, and new seating, even though it just hit 80,000 miles one has to look very close to see signs of wear anywhere in the coach, build quality does make a difference along with how it is maintained. This is not to say it is perfect, the floor inside the cabinet under the kitchen sink where the trash can sits has some damage (looks like a drain cleaner spill ate into it), and there are some fine scratch marks on the kitchen table, but those could probably be sanded out and resealed with little effort, the carpet on the entry steps is also showing wear even after being cleaned even though it is only 3 or 4 years old.