For most manufacturers there are RV Clubs as well as forums. You may need to do a little research online to locate a club. To me that would be the best source to ask club members how they feel about the quality. Forums as you know aren't the best source but if you find a forum dedicated to a manufacturer and various models you may be able to determine good or bad by the posts on the forum.
Other than that I would trust your gut. I recently walked into a high priced toy hauler and as soon as I began looking into cabinets and closets and other areas where I could see the construction methods used...I was not impressed. Based on the construction I would have expected a much lower price.