My rules.

1. No Flood cars period. If it was in a hurricane zone or has had flood damage the answer is no.

2 You can typically see the damage to the car on the internet. Most total loss cars are sold through internet auctions IAA and such. So if you google the vin number and look at images you can usually see the damage. I tend towards less damaged cars especially if it is fenders and cosmetic vs major drive train suspension issues.

3. If I have any doubts I take them to a collision repair shop I trust for an inspection. (I am an insurance agent so I am lucky they do it as a favor to me)

4. Insurance companies are totaling cars for really minor accidents now. It used to be hard to total your car now a fender bender can total it. Often times branded title cars have less damage than other cars that have had accidents and been repaired.

5. Long test drive. I take them on freeway to get them up to speed. Back roads to check how the brakes react and if they pull one direction. Check the alignment and make sure it is not pulling one way or another.

6. Try and avoid frame damage if you can. Frame damage is not the end of the world but it scares me.