Update July 2023: Added new mixing platform Thormixer.io, thanks to Loyce for bringing it up.
Some quotes for archiving purposes:
The platform runs a scoring procedure for each incoming coin so to check its reliability
The service liaises with crypto stock exchanges
Coins with dark history are never let in.
It's funny to me how first they claim they only allow coins without a 'dark history' ([insert usual mantra of:
taint does not exist,
all coins are equal,
Bitcoin is worthless otherwise,
no definition of clean or dirty is given, ...]).
While shortly after, they claim their service 'cleans the track record of people's coins':
The algorithm carries out multi-layered cleansing that achieves a clean track record for your coins.
If coins are already 'clean', there is no reason to 'clean their track record', right?

Some people really try to sell a product without understanding that their whole concept makes no sense..
'I sell washing machines that only clean already clean clothes! Please give me your money!'