also, brands can shake off stigma. people still drink coca cola even though the company once used cocaine in the drink.
Once the general public accepted a product, its name does not care anymore.
Porblem is cryptocoins have bad press, dark is associated with bad activities, private is associated with legitimity. That's the whole difference between Darkcoin and PrivateCoin (for example) in the ears of the global audience.
Why did you have a Darcoin Wallet? TO buy drug,weapons,porn?
Ho, you have an AnnonCoin Wallet because we fought for our freedom,autonomy,rights.
Of course in the 2 case, you do exactly the same with your coins, but the global audience did not think of you or the shop that will (or not because of that) accepted the coins (or juste feelings about the coin) the same. This is not a problem if the global audience is not the target of the coin, but in order to be accepted as main coin, and used on shops like tiger-direct, I think it could be a problem, and that a clone with darksen code will do better.
BUT I'm French and may be the word DARK is not feel the same in other language.