Some of the exterior skin in the back has pulled away, but from the pics looks repairable.
Without good pictures it is hard to guess, but almost always when skin is pulled away it is because the screws holding it to the wood frame have lost their holding power because the wood is rotten...
MOST old trailer owners do not have any idea what kind of damage is hiding behind "its just a minor water stain" or " the skin is just a little loose, a few screws will fix it".
This trailer, if it has no more than cosmetic damage is probably worth the asking price, but if there is rot in the structure, it is no small job repairing it and the asking price is more than most familiar with this kind of repair would be willing to pay.
You might consider writing to Nancy, the head of the Scotty club.
http://www.nationalserroscotty.org/resources/index.html
She may be able to help you with values and if you buy it, repairs.
Rob
Waiting for "someday" will leave you on your deathbed wondering why you didn't just rearrange your priorities and enjoy the time you had, instead of waiting for a "better" time to come along...