Bitcoin tumblers take care of this. Roughly, you set up a service that puts a lot of people's coins in a single wallet, then you route bitcoins from that wallet

Bitcoin tumblers take care of this. Roughly, you set up a service that puts a lot of people's coins in a single wallet, then you route bitcoins from that wallet to a bunch of different wallets operating in similar fashion. Kind of like how TOR works. It's easy to generate many temporary wallets that can not be linked back to your main wallet, shops can do this too and I think it's considered a good practice to use one address per sale. You can also convert the Bitcoins to a more anonymous coin (Monero?) and back.