[openasocket]

No reputation system is perfect, especially in an anonymous setting.

For the second issue, I guess they wouldn't do anything (though I'm pretty sure selling drugs to someone in a country where it is illegal is always illegal). But unless the only dealers on there are doing that they can still pretty easily catch dealers. And, even with a perfect reputation system, once you catch a dealer you can locate the addresses of all the customers he sold to and bust them, or keep his online business running for a while and busting buyers until his reputation runs out.

EDIT: actually, does Ethereum even allow for hidden information between two parties? Isn't it just a public ledger so everyone can run the code and verify? That means anyone could get all the shipping addresses

[TylorF]

For messaging you'd have to use some sort of public key encryption to protect the message. When thinking of platforms like Status.im I wondered the same thing for messaging, but they also have an actual client, not just on the blockchain.