Clean a Wacom Intuos mouse

Step 2 A shave...

Using a disposable razor:
Preferably one with more than one blade (this leaves a nice, clean surface on the felt). Shave the bottom like you would normally shave, well, yourself. Don't push down hard and don't angle the razor too low or it will take off chunks of the felt and cut into the plastic along the edges of the mouse. Go slower along the edges to avoid nicking the plastic. Also go a little slower over the sticker in the center to avoid cutting the edges of the felt.

Any other type of blade:
Hold it perpendicular to the surface of the felt and scrape LIGHTLY. If the blunt side of the blade is about the same thickness as the cutting edge and you can use that to scrape without cutting yourself, do so (the non-cutting edge of an X-acto knife works very well). You don't want to scrape too hard or at an angle because it'll take off bits of the felt.