I'm wondering if this is anything to be concerned about. I haven't used the cables yet, this is how they looked straight out of the box.
If it really bothers you, take a q-tip dipped in alcohol and wipe it a couple times, it should disappear.
You've never used a Sharpie before? That's not coming off.
Actually I have. I used to work in media management at a software firm. Sharpies were the best at not eating into the foil back of a CD and damaging the data but they can be removed from many plastics with Alcohol and a cotton swap (Lighter Fluid or Brake Cleaner work to a lesser extent.)
How To Get Sharpie Off Plastic Without Damaging it (homedit.com)