Believe you me, I have witnessed people "leaving" a gem of a car only because it was repainted, and rather painted better than the manufacturers. I understand that there lies a little doubt that a re-painted car might have got a major hit, but mostly such chances are 1/10.
Once I was searching a car for a friend and ended up in a showroom where a 5th Gen Civic was for sale, the car was "black", or used to be black but not anymore, as 40% of the paint was faded away and you could see a variation of greys and the primer. But to my surprise, the owner demanded a hell of an amount and constantly repeated "Genuine paint hai!". I wonder!