Wow, some of the responses here really make me laugh.
Different paint thickness on purpose?
Are you people bodymen in real life or do you just play one on the internet?
A magnet will do absolutely ZERO for the paint thickness and will very rarely show any bondo except in the case of a huge amount. Even a thin refrig. magnet will go right through a professionally laid on filler.
Extra thick paint from the factory? That is hilarious. Cars are now and have been for years sprayed by robot to exacting standards. All panels get the same amount.
Aluminum panels needing more paint? Give me a break. The aluminum saves weight, period.
The average person will not be able to detect body repair that is even shoddy at best. A pro will detect even the best work as there are always signs, always.
The dealer will rely on a paint depth gauge to determine past body repair if it is good enough to the naked untrained eye.
Without seeing the car in question in person, I would say it was in some type of front end accident and there will be tons of signs, but for the OP, I would strongly take issue with the selling dealer. Carfax is a joke. Tons of accidents don't get listed and if the car was repaired for cash and not under insurance, it won't show either.
Although the owner already figured out (with traditional methods) that some parts were repainted, it is very good to have as valuable info and feedback as this one.
But you cannot be seriously interpreting a magnet would be used to measure the thickness of the paint, perhaps you know how a magnet works on aluminium versus steel?
I did not know that aluminium cannot be painted with more layers of paint or other stuff because it is supposed to save weight, now that you explain that thoroughly, it is all clear.
I thought aluminium had other advantages in addition to weight...
Of course I've never heard of robots at the car factory but now that you tell this, can you explain the coating process on aluminium versus steel? Are you saying that robots cannot prepare aluminium parts separately before those are assembled and the car gets painted? Honestly I've never had to learn the coating difference and would be happy to see this explained. One would not have to be too clever to understand that these are
different at least for rust protection.
PS. You probably are a genius on technical items but a whole lot of life is communication with other people and I get a feeling you could improve there.