Working at an RV service center, and also doing pre-buy inspections on the side, I've seen a decrease in the overall quality of the entry level units. Poor manufacturing is mostly to blame, not just on the RVs but also on the appliances. We probably sold 30 AC units this summer, half of them going on 2-5 year old units.
But Grit has hit on what I believe is 50% of the problem. I'm constantly amazed by how much RV owners don't know about their units. Some of this can be attributed to new owners, but even seasoned owners are making some pretty dumb mistakes. In fact, a good portion of my inspection business is "I just bought this RV and I have no idea how it works".