I have had two new TrailManors, and am very happy with them. 2007 is a different animal, as it has been used for 8 years, and you have no idea if the owners maintained it, or not. If not, you could be in for a lot of repairs. If they did maintain it, it could be in wonderful shape.
Only way to know is to look at it. If you can see pictures before going to see it, it should appear to be almost new. If you see chips out of counters, rips, dents, etc., chances are that it was not maintained, and would be a pain. If it appears almost new, that is a possible indicator the previous owner took good care of the unit.
As with any trailer, how it was maintained directly affects its quality. TMs are normally built well, but all, as any trailer, seem to have issues upon delivery. My issues were minor, and easy to correct.
I love my TM, and don't plan on getting rid of it. It is easy to tow, good fuel economy while towing, and I can get it into places only a popup can go, which keeps most neighbors away (I boondock most of the time). :B
Good luck!