It turned out that Emiliy had a serious UTI. After multiple courses of anti-biotics and steam cleaning the carpets (twice), the problem is almost resolved. Now she urinates inappropriately when she is mad at me. For example, I was kitty sitting for some friends of mine and I wore a pair of cloth sneakers over to take care of their cats. When I got home I removed my shoes at the front door and Emily came up to start sniffing them. She then very delibrately pee'd on only those shoes as I stood there watching her I took it to mean that she was telling me that she wasn't happy about the other cats