That camper is 24 years old. 24 years of use or abuse, maintenance or neglect. At this point, all that matters is its current state. The fact that it is still around says that it cannot have been treated all bad.
There was an article in Truckcampermagazine recently on how to evaluate a used truck camper. It is easy to find on their webpage and should have useful information.
2014 Ford F350 XLT 6.2 SCLB + 2017 Northstar Arrow