Yup, but it could go through time so it was ok.

They did. Amongst other issues.

DeLoreans, early-production models in particular, suffered from poor build quality as well as mechanical issues.

This quote ist taken from the English Wikipeda Article. In the German Wikipeda Article quality issues are described more detailed: many issues involved the gull-wing doors, which had a complicated opening mechanism that often jammed. Also one could injure their hand by closing the door, as it was too heavy. The German Wikipeda Article also mentioned, that, due to the choice of material for the body work, a proper alignment of the stainless steel panels was not to be expected.

Edit: to reference to the original question: I haven't found any statements regarding to the pollution of the stainless steel body, but I can imagine that this car had the same issues the Cyber Truck is having.

Imma blow your mind, but all cars have this same problem. Literally any car that doesn't have ppf film on it should have bird poop and bugs cleaned off ASAP. It will discolor your paint, make it chip easier, or at worst make it completely fall off in that spot. Especially if you live in an area where birds have access to berries and stuff that can make their poop even more acidic.