Which travel trailers makes and models are low quality ?

All of them or none of them. It is a matter of perspective. Due to their nature, they have to be lightly built. The appliances installed in them are all made by a few manufacturers, which I consider equally good. I would look at how the roof is made and things like self-leveling jacks etc. Many people buy them and hardly ever use them. Look for a used one that is in new condition. The savings would be substantial. Make sure you have a vehicle strong enough to pull one. Good luck!