I have had 2 iPad 2's... the first one was easily scratched by the smart cover, as I missed attaching the cover to the side of the iPad. I watched it not connect and graze over the screen, leaving a nice scratch about an inch long.
A couple of things come to mind: The first is, the more I worried about any of my apple products, the more it seems to scratch, drop, etc... I think the condition of any Apple product I ever owned was my 3GS, that was given to me when my 3G died. I didn't put it in a case, and didn't put a screen protector or anything on it. Had if for close to a year and never once dropped it, nor did it ever get a scratch. Can't say the same about my original 3G... put that in a case from the beginning and within 2-3 months notice scratches on the screen (although it was in a case). Is there a point to this... for me, being careless is one thing but the less I worried about it and the more I just enjoyed it, the better condition it was in.
Maybe, just put it in a case when you are taking it out of the home... seems to work for me... but don't let anybody tell you different. It can happen very, very easily from a multitude of things.