I look for cosmetic damage no frame damage. I check them out with my mechanic and a body shop guy I know to see if fixed correctly. I do not buy Water damaged cars especially in costal areas. Water can cause long term electrical issues that I do not want to deal with. Make sure your insurance will cover them. Allstate and several others will not.

Working in insurance I will tell you that insurance companies due to rising repair costs are totaling cars way faster and for much smaller damage now than ever before. The old rule of thumb was in order to total a car it had to have 70% damage to value on estimate. I have seen a lot of cars totaled for 8K damage on a car that has 30K value. I am not sure why this has become so prevalent but now more than ever you can get some really good deals on salvage title cars that did not have major damage.