Mountain Lion seems to be having a bug rendering app icons in Launchpad. But as with any other bug, there’s a fix for this. Let’s now take a look at how to fix this issue.
The issue seems to be with the Mountain Lion’s icon rendering engine, and this can be sorted out by clearing off the icon cache from the icon DB and then, regenerating it to get the original, non-blurry icons.
Regenerate blurry icons in Mac Launchpad:
Fireup Terminal on your Mac and just run the following command:
sqlite3 ~/Library/Application Support/Dock/*.db "DELETE from apps WHERE title='NAME OF APP';" && killall Dock
Remember to replace the NAME OF APP with the app that has got the blurry icon on the launchpad. At this stage, the icon would have disappeared from the Launchpad. Now, go to finder, and drag and drop the app to the Launchpad.
This would fix the issue. Hope this helps.