Had an interesting question from one of my clients earlier today about whether my Bitcoins were "clean" (as they are either bought with cash or through legal services like the Bitcoin Stock Exchange). He suggested I make this a selling point of my Bitcoin trading service but I am very reluctant do so as I think it would be misleading!If you think about it, the coins you buy from an exchange could have come from anywhere - in the same way I suppose as money you withdraw from a cash machine might have been used to pay a hit man at some point!Also even if you only offer legal products/services on SR, every user who orders from you has their coins run through a mixer so I assume that the money of the great and the good is mingled in equal measures with money earned from less savoury activities? I certainly tumble any coins my clients order before sending them on!As such, I would say the only guarantee of obtaining "clean" Bitcoins would be to mine them yourself? I'm more than happy to be contradicted on this point but I just don't think it's helpful to think of BTC as being "tainted" or "untainted" in this way.Looking forward to your comments,V.