No, that’s not nonsense. For that price, there are exclusively objects that need to be renovated. They are barely habitable, but nothing more. You have to invest the purchase price again - that’s the average. I’m from NRW and know the area well. You yourself say "can be well renovated." Just replace CAN with MUST. Then it fits. The house is not a bargain; for €200,000 there are also "good" houses in these weak locations.
But why are houses considered junk just because they need renovation? It’s obvious that you have to or rather should do that. That you get used houses where you only paint the walls and can move in is rather rare, logically not at that price either. And the price is obviously adjusted to the condition. That’s not junk, that’s quite normal. And whether you have to renovate a house is another matter. Personally, I would do it too; we have done it ourselves. If your argument is followed, then our house was junk too. But it wasn’t. For me, junk properties are those that really have no value left, where there’s no return anymore, at best if you want just the land.
As long as the moisture issue can be resolved, you can probably turn it into a nice little house for the normal budget. It becomes a junk property if in truth dry rot has already spread and the place can really only be torn down.