When I first got my van, the rear air vents had rotted. Someone had carefully recreated them with...filler. Looked quite good, actually.
10 years before we met, one of my customers had had a filler job done on purpose under the arches in that there London because it was multiples£ cheaper. It had lasted pretty well. The rotten bits were still rotten.
Am I alone in having a begrudging respect for whoever applied kilo upon kilo of filler and moulded into a car shape….must have taken ages.
I remember my father using a magnet to check the bodywork of a second hand car he was looking to buy.