Not that I condone criminal activity, but to be honest, that is how bitcoins gained some traction. I don't think any rational person will see the name darkcoin and say, oh, I can't use that, as it's an evil coin used for bad things. If so, they wouldn't use bitcoins or any currency either. It's not like someone made a coin called devilcoin (although give them time, they are sort of running out of names)....

Bitcoin - litecoin - darkcoin    ... has a nice ring to it, and perhaps darkcoin becomes the copper to litecoin's silver. Although litecoin isn't doing particularly well either lately.