One can now mainly argue about this if one were the party and the opposing party ;)
1) Duty to inform due to a concrete question: here the question: has the basement ever been wet? If the seller claims no and that is not the case, he has not fulfilled his duty to inform
The question only came up after the purchase?! But it hardly matters
whether the basement has ever been wet. Some basements, just to stick to the example, are wet more often. Then it dries or is dried, and all is well. Usually, you have more problems with the household goods when professionally dried.
More interesting is the
reason for the moisture one suspects here. Has it been stopped? Or is there a leak that causes moisture to repeatedly occur? If it was a washing machine, I would politely dismiss this topic and look at more important rooms. However, this situation does not seem to be the case here. Because there are signs that something has been done. By the way, these holes can also have other causes... as I said: you can smell moisture, feel high humidity... with a good nose you can also smell mold if it is there :)
2) Duty to inform without question from the buyer: here there are certain issues that are to be regarded as such, you yourself have already mentioned asbestos...... this also includes, for example, a damp basement due to missing basement insulation.
But the seller must first be aware that something has been installed or is missing.
As a result, the contract is canceled and invalid. The buyer can therefore reclaim the purchase price.
If only it were that simple. It is not. It is expected of the buyer before a purchase that he seek expert advice. That is why the contract usually includes the clause "sold as seen". And yes: fraud and deception are certainly not trivial offenses, but I still do not see it here.
Have a nice weekend
P.S. By the way, with these "holes" I rather thought of impressions from construction rods.