The issue remains you don't know the source of the coin of the other people you're payjoining with. If it looks the same as a normal spend with two inputs, and the other input is a darknet vendor, you will also get flagged as such.

As @TheBTCManual points out, and as I agreed and elaborated on here, as coins continue to circulate, this type of analysis will effectively become useless.

However, the analysis algos heavily factor in the number of "hops" between the address they class as shady, and the address you send from.

In other words, coin that was withdrawn from a DNM ten wallets ago is less of a red flag than coin that (looks like) it was send direct from a DNM into your wallet.

Through this lens, it's possible payjoin's ability to blend with other transactions could actually make your coin more likely to get flagged by a CEX.

I say this not to FUD either coinjoin or payjoin, but rather to point out that privacy and CEX's don't really mix.