Not sure you've thought this through Frank1.
First off I mostly agree with you that Darkcoin is pretty useless at this point, and may (probably will) completely fail, but you've got the wrong idea about anonymity.
If I go in a store and pay cash for something it is semi-anonymous. They might have cameras, or I might see someone I know, but nobody is getting my address, or tracking my buying habits as long as I don't use a loyalty/credit/debt card. This is somewhat true with bitcoin also, but will become less so. Eventually someone's going to start keeping track of what addresses do what, and after gathering enough info they will be able to peg and monitor many people fairly accurately.
My point is that you seem to be indicating that things like Darkcoin or Dark Wallet are only for nefarious activities, so "normal" businesses wouldn't want to list that they use these "dark" services. But I think there are people (not a lot of them) that don't want to be tracked and may chose to use Darkcoin if they can find places that accept it. Thus, they need to be listed in directories.