I have seen these trailers in the campgrounds and like the appearance. The important thing to consider is the care and maintenance the trailer has had. A good trailer can be ruined quickly if not maintained. If you are not savvy about trailers take someone with you who is. Same as you would hire an auto mechanic to inspect a car you want.
Things like stains on the walls or ceiling can mean a leak, soft floor can mean deterioration, etc. Operate ALL of the systems. i.e. furnace, water heater, refrigerator, stove/oven, onboard water system, city water system, lighting, AC, vent fans, faucets, shower, etc. Get the picture? This is where two pair of eyes are better than one. Have them plug it in, run water into the fresh tank for the pump system, connect the city water. Make things work.
Check the exterior for damage and discoloration. Check the tires for wear. Pull at least one wheel to check the brakes. Take your time, be thorough. That's the best chance to make a good deal and get a trailer you will enjoy for years to come.