news of drug trade do not register on most people's mind, so when bitcoin is linked to that area most people just shrug their shoulders - they just think it is something that happens to other people.
but when something is linked to underage pornography, society gets very, very emotional (whether that is appropriate, is another debate).
sooner or later, if not already, bitcoins will be used by some people in the trade and making of underage pornography. and when that happens, expect bitcoins to be attacked with overwhelming forces by governments and law enforcements and lobby groups alike.
Freenet is full of the stuff (unfortunately) and that the powers that be haven't yet cracked down on Freenet. Still flying below the radar? I don't think so.