There are, in my opinion, four major areas of concern about the quality of a towable RV.
1) Frame strength
2) Axle and suspension strength and quality
3) Tires and brake quality
4) Construction for water tightness
For me, (after some modifications) I am reasonably pleased with the first three items on my Jayco trailer. I am not pleased with the last item, and do not think I'd be pleased with any typical trailer. I think any potential buyer of an RV should be concerned when reading reports of water damage that is not covered by a manufacturer's warranty. My understanding is that all towable RV's are constructed in about the same way - that is, panels of some material put together with screws and waterproofed by a combination of a roofing sheet, aluminum moldings, putty, and caulk.
Until buyers are more concerned about the basic construction of their trailers - and not nifty "bells and whistles" - we will all be sold trailers that are pieced together and sealed with caulk. But the American automobile manufacturers made a lot of crap, too - until they got some competition. Cost is a major concern, particularly for an optional purchase like an RV and competition has an influence on both quality and cost.
There's lots of advice and information in forums... sometimes it is correct. For example, all of my posts are made by a political appointee who got the job as a reward for contributions to my diesel bill.
2011 Jayco 28.5RLS; 2008 Chevy Duramax; Pullrite Superglide Hitch