I would love a service like this however your implementation is flawed. Please add user accounts with a feedback system.
Seems your post comes at just the right time. Instead of accounts...
Items are now signable via your bitcoin-otc PGP identity. You'll find items have a circle to the right of them that shows the status of authentication and allows the user to "sign" the item if they so choose. If an item is signed click the check mark in order to view the sellers ratings. Note an item can only be signed after it has been created.
