If all they are doing is sending bitcoins from different addresses, why not just do this yourself? It isn't too hard to setup a few different wallets and send coins back and forth between them at random.
I mean, maybe I'm missing something here, but 5% plus transaction fee adds up to a lot for something you can do yourself.
Can someone with knowledge please post an answer for this question from echris1. Especially if you add Tor in the mix, is it not very easy just to anonymize your own coin trail with a bunch of self initiated / self receive transfers?