Q: Greyish Smudge marks behind the glass screen.

I can't even express how disappointed I am to have just noticed this on my iMac and within seconds found FOURTY FOUR pages of comments from users with the same problem.  I switched to Apple products for the hassle free experience, I got the biggest, badest one they had - and now this. UGH!

Experiencing the same problems here. I think Apple really needs to take this problem more seriously since it seems pretty many people are experiencing this. My iMac is just a week out of warranty so I am really into doubt what to do. Since not all repairs seem to have good results in the long run.

I have 4 27" Apple Displays and each of them was bought within the last 6 months. Unfortunately all of them have the clouding issue. I have all four connected to a single machine as I am CEO of a software company and our software is webcasting so I use the monitors to communicate with my desperate company.

While they are under warranty and I also have Apple Care this from a logistics and time stand point is very frustrating and apparently according to this thread replacements will only fall victim to the same poor design.

I really like Apple products but this needs to be addressed.

Since recollecting my iMac after it's first screen replacement on June 18, 2011, it appears my current display suffers from an extreme and worsening yellow tinge creeping up from the bottom left corner of the screen. I'm still covered under Apple Care until April 2013, but that doesn't mean I'm happy about having to lug this thing back to the store for repairs (again). I'm holding out hope for a recall.

I also have had the same problem with an iMac  27 ", purchased new Sept. 2011 from an Apple Store in So. Ca.  I recently noticed the same greyish smudging over my entire screen and took it in for repair. I was told it was an "environmental issue" and that they would replace the LCD but may not in the future. I did purchase Apple Care.  From what I have read in this thread it is either a dust or heat issue, either of which are obvious design flaws. I purchased dust filters  made for the iMac 27" from Amazon (uploaded pictures) and plan to use SMC fan control to bump up the fan speed to decrease the inside temperature of the iMac.

Think this will be enough to prevent it from happening again?

I am afraid that you can reach reverse effect. Look at my smudges.

As you can see the most annoying is in the SE corner (N and NW is also disaster area) and looks precisely like a burn (walnut type curves). If it was dust it will definitely have another pattern (waves, circles or some type of a more consistent shape). And if it is caused by heat - your filters will actually reduce the speed of airflow. Although probably applied to a new machine filter can help reducing future blockage of airways. Never heard of extra fan for iMac. But on the other hand it is ridiculous - Jobs wanted them out to make macs quiet. Fans strike back. Can't comment more as Apple censored me. Actually they read posts. But they say they wouldn't answer us (users). And we (users) only can discuss tech part of our sorrows between ourselves. No other comments. Loosers anonymous. In the meantime looking for advice about a solution to find out temperature inside my iMac, pretty soon I can't see anything on upper third of my screen. I like dark backgrounds now a lot.

I am using iStat Pro which is a free app for monitoring all sorts of parameters  ( including temperatures) on your Mac. Here is the link;

http://islayer.com/apps/istatpro/

Ahh,

always thought it was just affecting me. Glad to know that it can be cured for some time.

I shall sell this machine and tell the buyer that the cloudy pattern is part of the iCloud. Problem solved. I guess. My iPhone contract will be terminted soon as well. An iPad i do not have. Time to think oabout alternatives. Last but not least my paid Apple develover contract is about to end.

Yes, time to make decisions.

I can not believe that after all the problems I have had, as discussed here, I just found this post by accident.  I had the glass on my 24 replaced over a year ago, and again just two months ago, just days before my warranty ran out.  There was NO mention of this existing as a problem, or that there was even a fix for it. The guy who came here this last time seemed totally puzzled! I am going to call on Monday and scream my head off, and demand something be done in this case.

Same grey smudge issue for my mid 2011 27" iMac.  It's all across the top of the screen and down the right side.  At first I thought it was some kind of burn in issue.  Followed an Apple suggestion of creating a white jpg the same size as my resolution and using it for a screen saver (turn brightness down to save lamp life) and leave it up for a while.  Had no effect.  Followed another suggesting to set my background as white and take a screen capture (cmd-shift-3) and check to see if the smudges are visible in it.  They weren't so I'm pretty sure it is dust behind the glass. 

I'm under Apple Care so I called Apple support.  I don't have an Apple store nearby but have authorized service provider local.  Was suggested to take it in for them to pull the screen and clean it.  Support person I spoke with was cordial and helpful.

They can clean it from here to eternity, and in no time, it will be back.  I had the glass changed twice, and now, in less than two months from the last repair, the smokey fingers are backk with a vengeance.  This is a basic design flaw in these models, and there should really be a class action suit filed to force Apple to replace all these computers.

This is a photo of what ine looks like

Are you a smoker Leslie?

No, and I have two other iMacs in the house, a 27 and a 21, which do now have the problem.  The 21 is about two years old, and the 27 is about a year old.  The 24 is just over three.

I am angry, very very angry, I take the 2 iMac Thursday of last week from authorized technical center in Turin Italy and Friday one of these iMac come back for repair again.

The technical center explain me that the problem will be not definitively solved, that is necessary to contact Apple or buy a pc.

I spent a lot of time and fuel until now and I wrote also to iMac team.

Also my brother has the problem with his iMac and now wait the visit of Apple person from Milan.

I request also the ram update from 4Gb to 8 and I found on my iMac 12 Gb, incredible, and in order to avoid discussions I payed for this.

I use these computers at home (clean and without smoke) not in the mine in the same position where I used for a lot of years different monitors, from different brand, without a problem.

At this moment was not possible to speak directly with Apple responsible and I hope that the Apple person read these pages.

After 45 pages in this forum and pages and pages in others forum about this problem I think that is a serious problem.

What happen after the warranty if the problem is not definitively solved?

In Italy the price to change the panel is more or less 700 euro and I have not the possibility to spend this money.

After 20 years that I use the computers this is the first time that I am in a similar situation.

Best Regards to all from an ex enthusiast user.