The subject of claimed tainted coins could be a problem (or risk) in the future, if you want to change your crypto back into Fiat and no longer find an exchange, that does not makes two categories of crypto.

Of course you can go to an exchange, that only ensures that buyers and sellers find each other. For example person A) who wants to sell their crypto against Fiat and person B), who wants buy Crypto against Fiat. Person B) directly get Crypto from person A) and person A) directly get Fiat from person B) by providing his bank account number.

BUT: In this case there will be a bank involved.
There were cases in Germany, where person B) has tried to wash his Fiat by buying crypto this way. The bank account of person A) was closed without giving an explanation. (So we could say in this case there was "tainted Fiat".)

-> So when you try to sell your Crypto to get Fiat with a DEX/P2P, you will run into the risk of tainted Fiat.

The only remaining possibility then would be to meet each other live in person with Cash Fiat and Crypto.
But: That would again entail other risks. *haha