^ I went all the way back to the original post and zoomed in the pictures. Those sockets have a coating on them. Not seeing them personally I can't say if its paint, zinc coating or some kind of powder coating. I stand by what I said, that it's not the bolts fault. If the coating that was applied is not specificly set up to handle the heat, cool down of those brakes then it would not take that much of a harsh chemical to get a weakened coating loose and off the bolt.
The bolt package is cheap PR, compared to this thread.
@z - http://www.metal-coatings.com/feature-product.php
Web site says protects against corrosion.