Thanks to Jaba23 and SeBiG...
For me this is just a very temporary help.
I have been digging around since days and also found a very helpful blog, which doesn't make me feel better because it seems to be no solution, just evidence and hundreds maybe thousands users with the same issue.
How can Apple still do nothing about it???
After reading that I decided to write to Apple's feedback and post quotes from many different users with the same problem...
I suggest that all people here should do the same and fill the inbox of Apple's feedback.
Here is the link for feedback to the geniuses who don't care about Apple's reputation!
I hope you people out there will send them all your facts and rumours so they can start to figure out how to finda cure for the customization, which isn't just for fun...most users need to organize their filesystem by customized icons or for graphic design!
So Apple MUST deffinitely do something about it, and as for my understanding they should give an update for 10.6 as well as for 10.7 users since the problem didn't occur in the good old 10.5 Leopard operating system.
No we won't all buy an iPhone and dance to the flute of their iTunes...
Shame and understanding...that's all they need to get!
Oh, I forgot to mention; this is what you will get after posting your feedback:
Thank you for your feedback on Mac OS X.
We cannot respond to you personally, but please know that your message has been received and will be reviewed by the Mac OS X Team. If we need to follow up with you on your ideas for improving Mac OS X, we will contact you directly.
We appreciate your assistance in making Mac OS X better.
Mac OS X Team
SO LET'S SEE HOW MANY OF US WILL GET CONTACT DIRECTLY.
PLEASE report here.
Thanks - mac - user -
The feedback page isn't quite as much help. Instead, go to the Web Sites list in Safari and choose Apple Developer site > ADC - Bug reporting. You don't need to actually be a developer to join. After creating an account, you'll be able to submit a bug report. These reports go directly to the engineers, so they're sure to see it.
Be sure to follow the submission steps. "Please fix this!" is not a report.
I don't see any "Quote" button, so I clicked "Reply". Is that the same?
EDIT: I see it is not. OK, here is the quote manually copied-pasted:
"It only works as advertised when going forward, say from 10.4 to 10.5, or backward over a minor update, like 10.6.1 to 10.6.0. But when going backward over a major revision, the version checker can leave some newer files in place, causing weirdness like this.
I am not convinced by the Apple article you mentioned. I would love to hear an explanation from the author of the article (just wishing) or from you as to how the Frameworks and Library directories manage to sneak out of the archive. After all, they are tucked quite snugly in the /System directory and the /Library directory. Both of those are inside the /Previous Systems when the archive is applied. Do you think the installer looks inside /Previous Systems to see what it can find? If an archive installation is inappropriate over a later reference release, why does the installer not have a check for that? It has checks for dang near anything else.
In summary, I'm saying that article is really truly suspect. Until someone can explain the installer's ability to mix items that are in the /Previous Systems archive with the new directories, I remain skeptical. A Windows installer can get things all bungled up because it doesn't do a proper archive (only renames the Windows directory, leaving the Program Files directory out in the open). In my view, OS X archive is effective for any and all OS versions when it comes to Library and Frameworks directories. What happens to the hidden base UNIX files is another question, but those have no Library or Frameworks.
For me, the problem starts with Safari.
I went in as root, and deleted Safari and replaced it with the same version from my MacBook. That version had been freshly installed on the switch-over to lion, and not updated a zillion times.
And bingo, I got a nice sharp icon.
Here's where it gets weird. I decided to do a "diff" on the 5.1.3 (old, blurry version) and the new (not blurry) version, so I temporarily added the old version back in a different folder. (The difference seems to primarily be in line ending types in the info.plist)
Well, somehow that "older 5.1.3" got launched... and bingo: the blurry icon came back.. even with the "new" safari copy.
But then I noticed this extreme oddity / clue:
I have 588 items in my root-level applications folder.
I view that folder (and all of my folders) as a list. I just now decided to view it as icons, to see how the Safari icon looked. (Fuzzy again.)
But here's the extreme oddity:
Every application icon -after- safari was blurry too! (Only generic folder icons were sharp.)
My icons are arranged by name.
Several hundred icons (from A to Saa) before Safari in the view-by-icon window are sharp and behaving properly.
Every icon after safari (except folders) is rendered from the smaller size: blurry.
Now what does THAT mean?
I found this article helpful in resolving the blurry/pixelated icon problem:
Move ~/Library/Caches (the Caches folder in your user library) to the desktop. Log out and log in. The icon problem was solved. Some cache was causing the problem. It would be interesting to know which app was creating the troublemaker cache, but it doesn't really matter. Apps will create a cache when they need one - the process might delay the first launch of an app a bit, but getting rid of the icon problem was worth it.
I didn't have to do the second step of the advice in that support article (delete /Library/Caches -- the system cache).
The fix I posted on Mar 4 2012 seems to be temporary, though it works for a while after the caches are deleted. I also found that removing folders from the Dock that contain alias to various applications cleared up the problem instantly -- too early to tell it the fix is permanent. (Perhaps this indicates a root cause linked to a Dock cache and/or preference?)
I have some improvements to report. I upgraded Logic. That fixed the Logic icon in the Application Switcher. I removed the Firefox link from my dock, launched FF from the Finder, then dragged the resulting icon in the dock up to my preferred location, and that resolved the FF icon display in Application Switcher. These were the only two apps that were giving me problems in the Switcher. Hopefully, the good times will last.