Richard S. wrote: grounds on top because it's code.
I"m a show me type of guy.....so show me! I'll bet fifty cents it's not in writing. Unless this is very new, I don't think code makes a mandate either way. All of my GFI sockets read both ways.
I was taught the ground should be down because if the plug gets loose, the last prong to lose contact is the ground. If the ground is on top and the plug comes loose you now have an energized appliance with no ground which I was taught is much more dangerous than something falling in and shorting out the plug & blowing a breaker. That is, what would you rather have, a spark followed by a blown circuit breaker, or an energized appliance surface that is not grounded?