If I had put a check mark on a chart for every time I plugged in our mixer, drill, toaster, vacuum cleaner, or (you can fill in the blank) with one of those two prong A/C plugs with the wider prong that goes in the LEFT side slot of an A/C outlet, my guess is that I have been wrong 75% of the time in trying to plug the cord in the wrong way. Of course it is only takes a few seconds to recognize failure and turn the plug over to finally get it in right. But it is annoying, especially when plugging into one of those under kitchen cabinet A/C strips that we seem to have a zillion of.
Solution: Put a white self adhesive dot on the big prong side of the electrical plug for dark electrical cords, a colored dot for white electrical cords.
Now the cord is marked to remind you to put the wider one in the LEFT side slot (the ground prong slot, should be at the bottom of the three slots). You may have to put some clear tape to secure it, depending on the shape of the plug.