Read somewhere recently that some cats are prone to intense seizures that get triggered by certain sounds, like clicking a pen repeatedly, keyboard typing, computer mouse clicking, or even heels across a hardwood floor. They aren't going crazy, they just can't help it. So if the cat suddenly charges face-first into a table-leg right in front of you as you're walking across the floor with your shoes on, it might not be doing it on purpose. It could be having a seizure induced by the sound you made and it really can't control itself.
When it launches itself claws-first at your face in the middle of the night though, or in the middle of dinner, then yeah, it's definitely doing those kinds of things on purpose.
