Auto body repair & detailing: spare tire compartment in rear bumper accident, report thanks, honda accord

Question
I've been told that one way to check if a used car had been in a rear bumper accident is to check the spare tire compartment (specifically, I'm talking about a Honda Accord).  If there are these gray or black plates welded to the original body frame then it probably had been in an accident involving the rear bumper.  Is that true?

Also, can a car involved in an accident be certified pre-owned by a dealer/manufacture with a clean carfax report?  Thanks.

Answer
I have never heard of any grey or black plates and welded to what? Accident reports to Carfax
may vary depending on severity. Don't quote me on this,but from my understanding they would
most likely have to be a total,or a salvaged title before it would be recognized at carfax.
                                               Hope this helps, Bill