Mixing is a thing.
Seems to me that receiving bitcoin from an address known for mixing should be an automatic red flag.
You could say the same thing if you'd live in Sweden and with "normal" money: "Taking out money from the ATM should be automatic red flag, since no one uses fiat except criminals to buy drugs."
Attempts to obfuscate sources of assets on a completely public blockchain could probably qualify as money laundering, in and of itself. Its not really much different than the cash -> casino chips -> cash launder (which gets reported to the government, or is supposed to).