Check under the carpet for dirt and debris, smell the carpet, does it have a musty smell to it. Look under the seat for all the same and any rust on exposed metal, lock closely in the seat tracks, it is tough to clean there. If you can reach the wiring harness under the seats unconnect those and look close for any signes of water damage. If you are able to get the vehcile on a rack you can look at the underside, typically there are areas that will still show signs being in water, look into small nooks the cradle is a good catcher of sediment. Hard for them to clean (and they usually do not bother). Did you have a car fax report run?? have the vin run by a dealer and see if they show a salvage title on it (good way to make sure there are no open recalls to!)
