the only problem is with carfax wont always reflect accident history.
carfaxs are only sent in when a certain threshhold is met from the insurance company, its more paperwork on their end. check door gaps and see if there is clamp mark on the pinch welds underneath the car. look for wavy ness in the paint or more orange peel in one spot then the others.
i couldnt tell you how many times ive dealt with customers bringing in cars saying " o well the carfax was clean so i didnt check for any damage"
