They also put the socket "upside down" for a Switched outlet
by Bruce Bergman
When the receptacle is Split and the light switch by the door controls the top half of the outlet for a table lamp, they put it upside down to flag it.
People still plug the alarm clock in there and don't realize it till they've been late to work a few times, waking up to either darkness or a flashing "12:00"... "D'OH!"
Also a good reason to Not have the GFCI or AFCI protection on your alarm clock receptacle - just like your Freezer or Refrigerator outlets, but they won't allow that option.
Of course, they want the outlets all upside down in new houses and all new work in old ones, so the ground is on top which messes that all up - I usually match the rest of the house and put them the old 'right side up'. Unless they're Split Switched, see the first paragraph.