A bitcoin is a bitcoin is a bitcoin.
The idea of banning "shady" bitcoins is a GTFO of here.
Yeah but this will keep happening like it or not, as long as people can see transactions over the blockchain, that's why confidential transactions and "integrated coinjoin" in a way (I think BIP47 is somewhat related to this idea) would be mandatory if we want to end with that. All of the transactions should be confidential transaction ON and "coinjoined" with random people, unless you want to do a clear A to B transaction for some reason.