I had this with my first one before I returned it for a dead pixel. Admittedly I didn't have a case yet because it was still in the mail, but I put it in my
school bag in a plastic page protector so it would be ok, but when I took it out, it had a light circular scratch on it. By the time my replacement
Nexus arrived, the case was already here, so it's been on since day one and I'm yet to have a scratch.
Nexus 7 (2013)
32GB Flo stock ROM and rooted
Nexus 5 "Stormtrooper"
32GB stock ROM/Franco Kernel and rooted
Motorola Xoom Z604
32GB running My Android 4.2.2 (Sold)
Galaxy Note N7000
16GB running SweetROM V9 (Given to Mum )
Huawei Ascend Mate
8GB stock ROM and rooted (Sold)
running SlimBean 4.1.1 (Unused)