To revert to normal icons:

Click on the Parameters icon in the OnyX Toolbar

Select the Finder tab

Uncheck the "Show hidden files and folders" case.
If all your icons look pale, you have probably enabled the "Show hidden files and folders" function in the Parameters panel > Finder. In previous versions of Mac OS X, only the hidden items were appearing this way by default. Starting Mac OS X 10.5.x, all files and folders are involved.
Click on the Parameters icon in the OnyX Toolbar
Select the Finder tab
Uncheck the "Show hidden files and folders" case.