UPDATE:
So here's the deal
I got my 'replacement' iPad 3 from Apple and you guessed it...... it was WORSE, yes worse, than the one I sent back. This bad boy was the worse one yet. Half the screen, literally half, was green and the other half pink. Now I've had them with patches of light green and pink but this one was dark green and pink, and the screen literally split down the middle with each colour.
I was straight on the phone to Apple Customer Relations in Ireland and they were going to send me another replacement. At the time I agreed but then decided it was time for me to go in store (travel an hour each way) hence why I didn't take this route sooner and get it sorted there. Bare in mind, this all happened on a Friday so I had the weekend to mull it over. And that's what I did, came to the decision to sell the replacement (for a loss) just to get it out of my hair and so I could get off the replacement bandwagon and start afresh. Sold the bad replacement for a loss over the weekend and went into Apple on Saturday.....
Explained to one of those nerdy Genius guys all the problems I'd been having and that I wanted to try a DY serial number. Off he popped (after a few weird looks) and returned with a DY. Checked it over, all looked good, home I go.
Switched it on and this one had yellow edges and a blue patch in the bottom left corner

None of this was visible under the Apple store lights, it looked near perfect. Blue is a new one to me. I've seen green, pink and yellow, even a combination of all 3, but not blue.
Yesterday I decide to go back to another Apple store, again not in my area, another hours drive each way. This time I don't even tell them about all the other bad iPad's I've been through. I just say, this one has a discoloured screen and I would like to do a return and re-buy. He agrees, and so brings me a new one out. I didn't bother to ask about serial numbers, nothing. I just open up the one he brings me (DM by the way), load a blank white screen and hey presto, there is it, yellow left side with dark top left corner when held in portrait. This was under the bright Apple store lights as well so I knew it would be real bad under normal light conditions. I tell the 'Genius' what the problem is and you guessed it, he couldn't see it. Luckily another customer was walking passed, either that or eves dropping and she piped up 'I can see it. Look, it's yellow, right there'

The Genius gets all flustered at this and goes to find back up with yellow iPad in hand. He comes back with another Genius, a girl. She is lovely, says she can see it also and says to the other guy, 'What's the problem? Do another exchange'. He looks pissed but does the exchange. A DY lands in my hands and I open it up, it's like de ja vu all over again lol. It looks good, I take it home. Genius looks happier now that I'm leaving
So here I am, 7th (or is it 8th?) iPad down the line and I finally have one that I'm 'happy-ish' with. Again, looked perfect in the Apple store but not quite as perfect back at home.
It is by far the best iPad 3 I have owned, no pink, green or blue at all. Slight, very light yellow down the left side which is not even noticeable in day light and can only be seen in a dark room like when using the iPad in bed at night. All the other yellow ones I've had have been noticeable at all times so I'm happy at least about this. No dead pixels, no dust, no hair, no scratches, dints, etc. It's a keeper.
I have come to the conclusion that there aren't any
perfect iPad 3's out there. I have been through 7/8 and each one has had some sort of screen tint/discolouration. What are the odds of that? Some are a lot worse than others and some are hardly noticeable. If you ask me, it's about finding one that's hardly noticeable and living with it. I had 1 from early on that was quite good screen wise but at that time I still thought there were perfect iPad's out there so sent it back in the hope I'd get that perfect one. I wish now that I'd kept it and saved myself a lot of time, stress and hassle.
I can't fault Apple Customer Relations though. They rang me back today to ask about the replacement, I told them I'd sold it as it was worse and bought a brand new one direct from the Apple store. They understood that I wanted to get out of the replacement loop and to start afresh with a 14 day exchange period. They have also rein-burst me what I lost selling it on and for all the trouble I have gone through. I now have a few quid to spend in the online Apple store which they are going to send me once I've made my choice. Very kind of them. Top notch customer service! Just wish their QC was the same
*Goes off to FINALLY play with my 'new' toy*