It's possible to de-anonymize Bestmixer's mixes by subset-sum analysis by looking in/out amounts.
bitmixer.io & coinmixer.se are offline now, however its still possible to use the bugs I describe in my thesis to reverse nearly all transactions which have ever been processed by these services.
In my thesis, I attacked coinmixer.se (at the time of writing it was the biggest centralized mixing service), however - except chipmixer.com1 - every other centralized mixing service I checked could be broken in a similar fashion.
https://bitcointalk.org/index.php?topic=5117328.0