im a CARSALESMAN , well was up untill a few weeks ago to move into real estate, ive been at volkswagen, audi, skoda, suzuki, holden ec... so seen my fair share of dodgyness.
here is a few tips i used when looking over a car(trade in) that were passed onto to me from others during my time
Check the bolts in the following locations
BONNET HINGES
INSIDE THE FRONT GUARDS
BOOT HINGES
SILL PANELS
LOCATERS FOR EACH DOOR
DOOR RUBBERS(over spray sometimes hits them)
if any of these have missing paint, or evidence of the bolts being removed (99 percent of the time the spanner will remove the paint on the bolt or leave marks on it) then the car has had panels off, generally meaning an accident.