Great article! I've never shipped to the wrong buyer...yet. But I have sold something that was no longer in stock...(or, I couldn't find it in my inventory.)
I also learned the hard way that when multiple buyers buy the same item from my store, they all have the same item number in selling manager. Not realizing this, I got one buyer very confused when I looked at the wrong sold item in selling manager and gave him wrong information. He left negative feedback saying I sounded confused. Guess I was.
I hope I've learned enough not to repeat those errors again.