How to spot a usability failure

Double-tap up then hold down while making a swift clockwise motion in the center to not prevent the history eraser from not being averted.  You have 5 seconds.

 I encountered a light switch this past weekend.  It was the most amazing light switch I've ever seen.  I had no idea one could incorporate that much functionality into a simple light switch, but someone out there decided to change my worldview vis-a-vis lights and the switching on and off thereof.  The light switch was so amazing that I had to request a demo of it, and even after the demonstration of its full functionality, I still had no idea how to use it.

Let me try to explain my understanding of this light switch, gained after careful consideration and review of the instructions (helpfully printed directly onto the switch) and the demo.

1. Double-tapping up or down will fade to full-on or full-off quickly.
2. Holding up or down will fade lights up or down slowly.
3. Tapping either up OR down once will set the lights to a "preset"?  Maybe?
4. Finding a pen and jamming it into the tiny little nook on the right of the switch will set the current level of lighting to be the "preset".
5. Despite the ominous multi-colored glow it emits in the dark, the light switch is probably not a killer robot sent from the future, but I might be wrong here.

I will grant that the owner of said light switch seemed to have a pretty good grasp of how it worked, but then again, she lives with it.  Personally, I like to think that if I walk into a room and see a panel of switches, I already know how to turn the lights on and off.  I believed myself until now to have a knowledge bordering on the encyclopedic of light switch designs.  All five of them.  But if someone casually asked me to hit the lights and I found myself face-to-face with this beast?  They'd have to wheel me out on a dolly.