Again: I think you're looking at this in the wrong way. There are no "coins from malicious sources", now you're buying into the notion of taint. That believe is being sold by companies who want to convince others they need to buy their "taint identification services". It's a business model, and it's very existence is an attack on Bitcoin. All I can do is warn people not to fall for it.

It's very simple: 1BTC = 1BTC. Without that, money can't exist. You don't complain to your bank about the cocaine traces on your banknodes, do you? Money gets used by good and bad people, and the current owner can't be blamed for anything the previous owner may have done.

So you're saying you risk exchanging your clean Bitcoins for dirty dollars with a criminal past? Don't you see the irony in that?

I've seen a complaint about an instant exchange: the deposit was frozen by the third-party exchange they used "because of taint". They claimed the user needed to go through KYC, and after that the money was magically okay again. It turned out they used Binance, and the funds were added to Binance's large wallet. Does that mean the "taint" is magically gone? Does it mean the exchange sells "tainted Bitcoins"? Or does it means there was no taint in the first place? My money is on the last scenario.