My bulldog used to do this, I believed it to be separation anxiety. She never did it when I was home, only when I was gone. Cadence would actually line up several pairs of shoes, in my bedroom, and it was funny, they would all be in the left/right coordination. I continued to keep my closet closed, it didn't take her too long to stop. I have honestly never heard of the bitter apple spray working, but give it a try. Hopefully everything works out. (It also gives your wife an excuse to go and buy new shoes)