I would say to contact him and get him to post photos more photos, etc. Ask him for specific area photos, that he would have to take and post if he owns the trailer. It is my understanding that people have been known to pull photos from already posted sales and use them. Get serial number of trailer, type of title. Have water system checked for leaks, black water tank, fresh water tank, do appliances work, inverter, etc. Is the floor sound, the frame good? What are the decals on the lower panels and front panels?? Could be a heck of a deal. Interesting that it hasn't sold before. The photos on the post make it look very nice.As you are already aware of there are a lot of scams on web based selling, Craiglist, etc. If Streamwood isn't to far from where you reside, take a trip to look at it.
Maybe someone in the area of the seller would look at it for you. Good luck!