Ghosts.

Lets say you had a ghost in your house, that changed appearances just slightly.
For example, a neat towel, would be hung angrily (and when I say angrily. I mean like, its just an angry looking hang. NOT that it was hung in anger.
Carelessness if anything.
But I digress; if things were changing so slightly, how could you be sure of your actions?

Ghosts man.
They can really fuck you up.