Yeah, it's probably a regional thing. Here in Colorado, most cars don't really get that gross. I take a hose to mine like 3 times a year and dry it with a towel and it looks pretty nearly pristine. They'll only get very dusty if you take them on dirt roads a lot, or keep them in a garage all the time without ever cleaning them. Ones kept outside will keep mostly clean due to the rain, with maybe a little bit of grime under overhangs, and some sun damage on the paint.