Even under the best of conditions cars can get a little dirty. Just everyday dust, dirt, and debris can build up and cause a car to look a little bit dingy. Now multiply that by about one hundred and that's what it's like driving on a dirt road day after day and that's under dry conditions. Add water to the dirt and you get mud and that's far, far worse. If you live in an area where it snows you're likely to encounter nasty mud for at least a few weeks each year as the snow melts and if you have summer rain storms you can add a few weeks more to that. Pavement helps a lot with this issue, but if you live on a dirt road, then you're out of luck and either you wind up washing your car often or you learn to live with the dirt and mud!