I've actually had them open a retail package and swap them. Typically they have white box ones though. I'm not sure if those are new or refurbished. I am sure that it doesn't really matter to me.
Took two cables in with shorts. Never abused, used correctly. Jerk Genius said " you pull these out holding the cord don't you? You twirl the device around while plugged in, don't you? You keep the cord bent at 90 degree angle because you lay in bed while it's charging, don't you?" I said no to all of them. It's a bad cable, stop trying to place the blame on the user, it reflects poorly on the company that currently employs you. He returned with two new cables and was really crappy about it.
The times I've had it swapped were no questions ask and I was in and out in less than 2 min. I recently had a cable from my iphone 5 go bad but because I had upgraded to a 5S and still under warranty, they just used the 5S in warranty status w/o knowing.