My kitchen plug falls out like twice a week, drives me nuts. You're totally right, it's always the socket itself going bad. Such a pain to fix though, right?
My old apartment in Chicago had the same problem with the garbage disposal plug. I finally swapped the outlet myself after watching a few videos. It took maybe 20 minutes and a $3 part from the hardware store. The new one grips so tight you can almost lift the toaster by the cord. It's really not that hard if you just turn the breaker off first.