Not that I'd try and buy things like that online but how can be safe to do such a thing using btc if all transactions are stored in the chain and with that information and a little bit of work you can track down the user?
Using VPN could help, together with mixing coins, but again... Using btc for illegal things doesn't sound like a smart idea...
On the other hand zcash could be more interesting for that type of transactions.
Example, a guy from my country blackmailed movie distributor asking for btc ( a big distributor) and got caught because once police start to look into the case they tracked him down within 72h.
As BTCMILLIONAIRE wrote>
It's not really safe for most people, because they don't understand how to use Bitcoin or the internet safely. If you really want to do this you should do a lot of research.