I provide AppleCare service and normal wear-and-tear don't even catch my attention. I don't kick a repair for scuffs, scratches, dents, or dings. But I've been brought:
--A MacBook that was "dropped a little." The hard drive had impacted so hard that you can hear the parts rattling around in it (I still have it);
--An iMac (Aluminum) with display problems. I opened it, found evidence of a liquid spill, and the customer's daughter confessed that her boyfriend threw a beer at it;
--A MacBook whose "case had cracked"... someone to remove the top case without referring to a manual and ripped the bottom case from its fasteners on the frame;
--A wireless keyboard that "wouldn't work." Turned it in for testing and, as it heated, water came oozing out of the battery bay.
All these people expected these incidents to be covered under the AppleCare warranty. If I'm brought a machine that isn't working due to a defect in manufacturing or the failure of an Apple- covered part, I'll do everything that needs to be done to get it fixed and the customer doesn't pay a dime (but if you've installed third-party drives or memory to which a problem is attributable, tough luck, Chuck).
But if it's drowned, dropped, or ripped apart, Apple is under no obligation to pay for user carelessness. Period.