I was not refuting any argument, just complementing my statement. But I see why you would say that. . Not right now, and probably not until people get caught, but eventually they might. Think about it, LE agent buys from a source and saves the bitcoin address. Upon further analysis they can either bust the source's depending on how good is the OPSEC or, they can let the source run their business while they keep tracking everyone who sends bitcoins to the bitcoin address. They could then trace the address back to the exchange (has happened before) or, if you're storing the bitcoins in a local wallet, they could easily get the IP associated with the transaction. Obviously LE doesn't read this forum as much as people make it to be, but that may change in the not so distant future. I have been watching them closely and I can assure you they are getting pretty good at this game, It's just a question of time.