There are thousands of cars circulating that have been damaged by floods and have been repaired by insurance companies or have been totaled.  There is entire market in buying and selling these used cars.  There is a huge discrepancy in the titling requirements between States for these cars.  Sometimes a dealer can wash titles (remove the salvage marking) completely legally and them re-title the car in another State with a clean title.  Your car could have flood damage or could have been totaled by an insurance company and you would not know.  Usually if the car had a salvage title it will show up in Carfax, but sometimes there is a delay.  You might only find out that the car had a salvage title when you try to sell the car.  New Jersey Law requires that dealers make known defects for which they are aware

To complicate the matter even further insurance companies have their own internal standards as to when they should salvage (repurchase) a car.  These numbers range from 80% to 90% cost to repair compared to actual cash value (ACV).  If an insurance company salvages a car and it falls below the state threshold requirements they might not have to salvage the title.  There are thousands of cars circulating that have been salvaged by insurance companies and resold at auctions without any title restrictions.  You could be driving a car that has been repurchased by an insurance company and resold at an auction in which they have a monetary interest.  To make matters worse Carfax would not pick this up because they do not have access to CLUE, Comprehensive Loss Underwriting Exchange