We just upgraded from a pop-up to a used hybrid - used 2003 Starcraft Antigua. We found one on a dealer's lot that they were interested in moving for a good price.
Bunk ends were solid, floors were solid, minimal evidence of water damage. Found water damage in the shower (not terribly surprising), had the salesman pull a ladder out so I could take a look. The dicor was not well-maintained, was ugly and in need of repair around the skylight and vent, but the roof seemed solid.
Fast forward a couple weeks and I've refurbed both the skylight and the vent. Based on how the original dicor was applied (screw heads weren't fully covered), I'm chalking it up to a manufacturing/assembly defect. Everything is water-tight now.
While working on the roof I noticed a huge gap in the dicor at the front of the roof. I've since caught up on the neglected roof maintenance and a recent rainstorm has confirmed this.
All that to say, be sure to check the roof!