No system is perfect. NONE. If the vehicle has a clouded title, that can be a big clue but NOTHING is foolproof, even when the vehicle is brand new.
Think about it. If you are unfortunate enough to be at the boat launch ramp with your RV and back into the water too deep, you stall. Your friend pulls you out. WHO'S GONNA KNOW? ANSWER: NO ONE BUT YOU!
If you can't inspect a prospective vehicle yourself for potential water damage, then hire someone who can. Water damage is almost impossible to hide to the trained eye. Check to make sure everything works and there are no signs of mold, moisture, corrosion, discoloration, delamination, odor, mud in unusual places, obvious excessive pressure washing, etc. It's really a lot like checking for previous accident damage. Suspect any vehicle that is too perfect for its age.
Beyond that, it's about all anyone can reasonably do although I'm sure others will chime in.
Chum lee