The "usability is like Sandpaper" quote should probably be attributed to Alan Cooper, who says the following on page 206 (not sure which edition I have) of "The Inmates are Running the Asylum": "To me, usability methods seem like sandpaper. If you are making a chair, the sandpaper can make it smoother. If you are making a table, the sandpaper can also make it smoother. But no amount of sanding will turn a table into a chair. Yet I see thousands of well-intentioned people diligently sanding away at their tables with usability methods, trying to make chairs." It's a good book. You should own a copy if you don't already. (He said, generally, to everybody in the universe.)