Taking Bob C.'s advice i read up on some interesting info posted on the americal veterans assoc. website about the CIB. The jist that i got was that you had to have a Infantry or Special Forces MOS to recieve one, although I have to imagine that plenty of other's without those MOS would have 'earned' one.
Would a soldier only have one MOS or would they have a few? I mean my grandfather qualified himself for weapons, and spent time in an infantry regiment, although it being occupation time, you wonder. I guess the CIB came with a raise as well. Could be another reason why they didn't hand them out like candy.