I agree that floor rot is the biggest problem to watch for. Scamp floors are exposed above and below, so it's easier to spot. Inspect inside all the benches and cabinets around the outer perimeter of the shell- anywhere it's not hidden by finish flooring. Tap with the handle of a screwdriver and look for staining. You can also look from the bottom, but most water damage works from the top down.
Take a small jack with you. These trailers have rubber torsion axles, which have a lifespan of around 20 years. Jack up one side of the trailer (on the frame behind the wheel). Make sure the wheels drop as the frame rises. Little or no movement means a dead axle
, which will run $600-800 to replace.
As to the frame itself, the most common failure point is under the front where the tongue bends. Look for cracks there.
Beyond that, the Document Center in the More tab has a "Buyer's Checklist" you can download and print. It will help you not to overlook anything. With a trailer that old, expect issues. It's up to you to decide if you want to deal with them, and whether they are reflected appropriately in the price.
If it has a 2- or 3-way RV fridge
, ask that it be started several hours ahead of your inspection. RV fridges cool very slowly. Fridges can be expensive to replace.
If possible, recruit someone with RV experience to be a second set of eyes, preferably someone who is not emotionally invested in the sale.
If it needs a lot of work, unless you have the time and skills to do it yourself, it's almost always cheaper to pass in favor of one in better condition, even if it costs more. Whatever your budget, leave some in reserve for inevitable surprises.