And I think this is absolutely silly. Speaking for myself, I could care less if my bitcoin was previously used to buy guns, drugs, or illegal porn. I'm sure the cash in my pocket has been used for similar shady enterprises. At least, I think that's what you're getting at.
I think it's not the crime of the Bitcoin's crypto currency if people use it to buy illegal things, it's simply their fault . People already use fiat and gold easily to buy this things before the Bitcoin's creating and still use this currencies to make illegal deals nowadays.