Always look first, then buy

Hello, I bought a used one yesterday, without looking at it properly (i.e. I looked at it already, but very quickly, without lifting etc.). I never really did, but was rather a spontaneous decision. This morning there were a few small “surprises” in the workshop: the car was probably painted from all sides and the tires are not registered for this vehicle. If not the end of the world (could get worse!), but it is annoying. Wa I’m surprised: was that on the part of sellers (privately) legally OK not to point out or to conceal it? Can one (and above all is worth it?) against it still something to do? Greeting