The WORST incidence of this was years and years ago. We lived in an apartment with a dark brown carpet, and had "borrowed" a cat for a few days who happened to to be almost all black. Well. I was the first one home, it had gotten dark out, the hallway was pitch-dark, the cat was lonely, and the light switch was about 6 feet down this dark hallway ... I must have kicked/stepped on the poor thing about 5 times trying to get to the light switch so I could at least SEE him! (He was insisting on twining about my ankles as I walked!) Fortunately, he was soooo lonely that he instantly forgave me, but I felt AWFUL!