Check for cracks on rubber roofs or rust and loose screws on metal roofs. Resealing a roof is a common but vital maintenance task.
Many veteran owners highly recommend hiring a certified 3rd party inspector before signing, especially for used rigs, as they can spot underlying issues like "delamination" that are hard for beginners to see. Checklist for buying a class a motorhome? - Facebook
Ask for all service paperwork and manuals for both the RV and its individual appliances.
This is the most critical check. Look for soft spots in the floors and walls , ripples in wall panels, or stains in ceiling corners and under sinks.
Open and close all slide-outs and awnings fully. Check the seals for tears and ensure the operation is smooth.