Here are a few interesting facts:
Cleanest stall in a restroom is: The one closest to the door. Because a majority of people use the one farthest from the door.
Dirtiest surface in a restroom: The floor. In fact, the study that she cited said about 1/3 of the purses tested had fecal matter (poo!) on the bottom from being put on a restroom floor. Use the hook in the stall to hang up your purse!
One of the cleanest surfaces in a restroom: The toilet seat that you sit on. So, if you bring a sandwich in to a restroom and need someplace to put it down the toilet seat might be a good location. Just don't put your purse down on top of the sandwich.