You cannot equate an Apple store display unit to an actual customer owned unit. They're manhandled by several people daily. People who will intentionally try to ruin or scratch it to test it's durability. A lot of times as a result of what they've read on the internet.
Before buying mine I went to 2 different AT&T stores and the Apple store to play with them. At both AT&T stores the phones were in terrible shape. One would not even power on and at the other store the back of the phone looked like someone had taken a sharp object and intentionally scratched the living crud out of it. The ones at the Apple store were in better shape but there were a few with minor cosmetic flaws.
While I was there, a kid was playing with an Apple TV and he dropped and shattered the Apple TV remote. His mom quickly picked it up, put it back on the shelf and shuffled him away. So yeah, these things get abused while they are on display.