Greyish Smudge marks behind the glass screen.

Guangzhou, China - same issue here. Has progressively been getting worse since I bought it 6 months ago. Now at the stage where it's all over the screen (greyish marks - in some places looks like someone has run their fingers down the back of the LCD).

Just searched and found all these posts about the problem, so will be calling Apple Support today.

what a pita - especially for the cost of this high end gear!

Just an update from my previous post, as my machine had the grey smudge issue - rang Apple Care - took the machine (iMac 27" - one year old) to the authorised repair centre, new screen ordered on Wednesday this week, new screen fitted today (Friday) and now back at home. Very good screen, no banding, no yellow tinging, no grey misting (hopefully for ever!). First class service from both the Apple Care Tech guy and from the repair centre. Shame it happened in the first place, but the Apple Care service has been first class - thanks. Hope everyone is treated the same way.

My iMac 27 appears grey smudges, too, in Beijing. I'm trying to get contact with apple and have it fixed. Looking forward to your result from apple. Good luck.

I'm having similar problems but I'm also getting something strange
It 1st started with the grey blobs, which you can see against a white background
http://i52.tinypic.com/vo4l03.jpg

But It is starting to get some weird ripple effect on it when on grey backgrounds
http://i55.tinypic.com/2e156ie.jpg

Which is a real pain as it affects images that I am retouching as I can't tell whats scrren & what's image

Has anyone else had these ripples?

Cheers
Andy

UPDATE. Brought it in to the Apple Store last Thursday. They had it repaired by Friday night! No questions asked and they did tell me that if it happens again they will fix it or replace it under the Apple Care coverage. Way to go Apple. Oh and by the way this was a $600+ replacement/repair so if you don't have Apple Care yet and you are still eligible, GET IT!

I had been noticing this on my iMac as well. Well, tonight it super SUPER heated and crashed. I cannot power it up. Attempts flicker multi color lights. I am a very very sad peanut 😟

An up date on mine.
AmSys collected as they said they would on the Thursday.
Had a text message Friday to say it had been assesed & spare part ordered.
Rang on Monday to say it would be delivered on Tueday - which it was at 10AM.
Screen has been replaced.
No problem with smudges, banding or yellowness - but I'll be keeping a close eye.
No hassle whatsoever from Apple, so I am impressed with that. Just wish it hadn't happened as it has dented confidence, and I'm uncertain as to if it will occur again. As others have said - Applecare is a must for these now in my view.
I am very impressed by the service of AmSys.

Having the same issue. Purchased Dec 2009. But I'm SOL because the warranty is up and no AppleCare. Researching DIY ways but not looking good. Seeing the amount of posts on this topic is incredible. Apple has a problem here and I hope they address it.

The exact same thing here in Greece. iMac 27" bought early summer 2010. I have not yet contacted Apple's Reseller (we do not have an Apple store in Athens) but i will, tomorrow morning, and will keep you posted on what happens.
In any case, it is a shame for Apple to have this same issue on iMac displays and not fix it for over a year now. Amazingly enough the first post on this thread is Jan 2010, one full year ago, and still no official answer on the matter at least to the best of my knowledge.
My problem is that as i see from older posts, even replacing the LCD will not fix it permanently. Can we keep changing the LCD's forever? I was planning on keeping my iMac for 5 years min. How exactly am I supposed to change my display every 3-6 months? Unbelievable...

Good luck to all of us with defective iMacs

iMAC 27. These grey smudge marks started to appear after only a month of use. Took it to the Genius bar and they were so shocked at the extent of the marks, they didn't even question the cause. Replaced the screen straight away. Had the new screen for 2 weeks and the marks are starting again. Clearly, it's not a problem with the screen but something inside the machine behind the screen that is the culprit. I could change the screen as many times as I like but the problem will always return. I'm so annoyed with this machine. I may just have to go back to PC.

Hey everyone,
I'm beginning to think that this has nothing to do with dust/dirt!
The metal casing around my screen gets quite hot!!! It is quite a lot hotter on the left side (where the marks are) compared to the right side!
I truly believe that these marks are from heat, and not dust!

I have the same problem, can anyone advise what apple are doing about this if anything.

it does not seem to be an isolated issue, maybe its time to take things further, after all as customers we do have rights.

Hi al,
It's "nice" to see I am not alone in this problem.
Just realize I got the same problem, probably since some time but only today during reboot (hence, white background).
I realized how big it was on the right top corner this cloud of spot.
it's the 27" and not even 1 years old.
I'll call tomorrow apple care and I will let you know if anything goes right/wrong

I reported the same issue with my iMac here before. Brought it to Apple store in Beijing (Sanlitun). They replaced the screen without any questions. My trust in Apple is back.

This is the second time that I have had this problem. Purchased my Imac in Jan 2010, had to get the screen replaced in August due to grey smudges in the top left hand corner of the screen. Apple replaced it quickly and efficiently and it came back good as new.
However, yesterday I noticed the marks again in the left hand side of the screen. Took it straight to Apple again for someone to look at it. I explained to the guy that after the first issue we have been extremely careful with things eg, candles, glasses of water as they said before that it could be something like that (smoke or water being sucked up) He jumped straight on the fact that usually this issue is smoke damage and then didn't stop going on about it. The Imac is in a smoke free house so I feel that there is no way it could be anything like that.
I feel a bit let down that this has happened a second time. Luckily they have said it will be replaced again free of charge, even though it is about 14 days out of warranty so I can't fault them but at the same time how am I to know that the same thing won't happen again.
The guy from Apple stressed to me that if it happens a third time then they won't be able to do anything and that its obviously something I'm doing with the machine which I find very hard to believe after reading all these posts 😟