I would say at this point, the problem is well known among Apple staff.
But, when I took mine in, I brought everything... the box, the cables, and the unactivated phone still IN the box with the front and back plastic covers still on it, to show that I hadn't even used it, and that it's spent maybe 30 seconds out of the box while I noticed the scuffs.
I made it a point to be courteous and calm, and point out that I didn't want to be "that guy" that goes through a dozen exchanges over the tiniest little things. But that if I had to make do with a damaged iPhone, I would at least like the damage to be my fault.
The genius I spoke to was very accommodating about it, asked no questions. He did try to buff out the scuffs, and when that clearly didn't solve the problem, he went right for a replacement.