Can I fix a shiny spot on my cloth mousepad by washing or rubbing it?

No. That smooth, shiny patch is permanent—it’s compressed and polished fibers, not dirt. Washing removes oils but can’t un-flatten them, and rubbing makes it shinier. A stiff brush and detergent might help slightly, but the texture won’t return. If it bothers you, buy a new pad, flip it if reversible, or just live with it—tracking is usually fine.