I personally use the Roccat Hiro mousepad and find it really good. Most of Roccat's mousepad lineups are smooth and doesn't get dirty easily, though I don't believe there are any mousepads that are completely dirt free. You can go through their lineup and pick the one that you would think best suits your needs.
http://www.roccat.org/en-US/Products/Gaming-Mousepads/Hiro-Plus/