This image of a model capture magnet was taken after an experiment in a Mars simulation chamber at the University of Aarhus, Denmark. It has some dust on it, but not as much as that on the Mars Exploration Rover Spirit's capture magnet.
The total distance driven on Mars by NASA's Mars Exploration Rover, 21.35 miles by early December 2011, is approaching the record total for off-Earth driving, held by the robotic Lunokhod 2 rover operated on Earth's moon by the Soviet Union in 1973.