Bring a magnet, screwdriver or icepick, and a camera.
Use the magnet to check the body panels for Bondo. If the magnet doesn't stick then there has been body work done there.
(read this in a restorers guide) Use the screwdriver or icepick and poke it through the rug. If it hits metal you're somewhat safe. If it keeps going then the floor panels are shot and need replacing.
The camera is for taking pictures so we can see the car.

That way you don't get one of these little smilies
