My first 16gb Ipad Mini was perfect--great color production, no defects whatsoever. I decided I wanted a 32, so I exchanged it and got one with brown splotches and some dirt under the screen. I did a warranty exchange on that one and got a brown boxed mini, which was flawless except having a remarkably pink tinted screen. Blacks didn't look black, whites were off, but the uniformity was good. It made reading text heavy sites like forums and blogs a headache, which is primarily what I do on my iPads. A jailbreak + color profile would have fixed it, but I didn't want to wait to rely on that for something I just bought.
I went in a few days after the exchange to return the 32 after trying to get past the pink. The lady was pretty cool about it and offered to grab new ones until I found one that worked.
The first one still had a slight pink cast, but was noticeably better than the last one, and actually better than all the display models they had out at the time. The retina 4 gens had the worst pink. This actually displays blacks and whites more to my eyes liking, so I walked out of there a happy camper.
It does seem like a lottery though. If I knew it was going to be like this, I would have just kept my 16.
All iPads I had didn't have any blemishes on the body, just maybe a few marks that rubbed out with my finger. I would have happily taken any marks / scratches for a perfect screen though.