[DoctorBit]

This brings up two problems based on the fact that very few people take the time to pay for and use a tumbling service unless they are trying to launder money:

1) Governments know that criminals use tumbling services, so there is a non-trivial chance that tumbling services are actually honeypots run by LEO's. If you think LEO's are not smart enough to think of this, consider freeway DUI checkpoints: a huge flashing sign across a freeway announces "Warning: DUI Checkpoint Ahead - Prepare to Stop." If you stay on the freeway, you'll notice that you never see any DUI checkpoint. The checkpoint was actually at the end of the first exit ramp after the sign - placed there to catch the fearful drunks that take the first exit after seeing the sign. (Frankly, I'm suspicious of publicly-available VPN's like StrongVPN for the same reason.)

2) Once your coins are tumbled with the coins of other criminals, the coins you withdraw from the service are associated not only with your own crimes, but also with the crimes of all the other criminals using the service at the same time.