I've had problems with wheel mice. The kind with a real wheel. I have small dogs and eventually the wheel will carry dog hair into the mouse and get caught in the wheel spokes. Really messes up scrolling. Sometimes you can open the mouse and clean out the wheel, sometimes not. I have gone to touch mice with no moving parts to solve this problem. Love the mice with touch pad strips for scrolling.

Dog or cat hair can also get into the bottom of the mouse, around the LED sensor and mess up tracking and even cause the cursor to jump around.