heres something to add to the ocd people's worries.
not only do you have to worry about tint. you also have to worry about brightness, and how 'white' the whites look.
sometimes i've gotten an ipad, no tint, uniform color... but if i load up apple.com the whites are different.
two indicator i look for, on the home page, the difference between the whitest part in the IMESSAGE icon. Also, compare the icons of the CAMERA, and see which one has a brighter gradient.
One thing to note also, alot of people who say they have 'perfect' ipads, might not be comparing two directly side by side, or might not have a 'good' one to compare it to, or think they may have a good one to compare to.
many of the rejects i've returned would've fared really well to my eyes had i not had a 'perfect' 32 gb to compare it to.
you think you have a perfect ipad? load up a gradient scale on google, and do the same for a few in the apple store and compare. i guarantee you, one of those screens will beat your screen in some way or another, weather it be brightness, better gradient or whatever.
One of my previous ipads had some kind of a tint to it, which made RED, YELLOWS, SKIN COLORS and other warm color look BRILLIANT, vs my buddy's 'perfect' ipad. however, when loading up apple.com, blue's, skies, and forums, his blows mine out of the water.
the 'perfect' 32 gb in my possession, has my ideal ipad screen, so i've been comparing it with every 64 LTE version i get, so far none have come to surpass it.
the 'perfect' 32 gb i have, isn't as bright as my buddy's ipad 2 tho,
so in the end man, you have to factor in brightness, saturations of whites, tints, uniform screens, blah blah blah.
heres what though, pick a screen your happy with, and would be able to live with. I'm all for returning ugly old looking screen with major yellow tints, pink green hues, etc etc, but if you think you're gonna get an ipad with perfect whites, optimum bright levels, full colors, no tints and uniform all around... you're gonna be wasting alot of time, gas, and causing alot of stress for the body.