When I was a kid, I lived in Moorhead, Minnesota. In the winter, the snow and the wind intermingle in sub-zero temperatures. Somehow, a bit of dirt gets in that clean, white snow, creating "snirt." So, after five minutes playing outside, all of us neighborhood kids would have a layer of mud on our coats and snow pants and boots, creating a cleaning nightmare for mothers.
Here's just one page of my "true story by a cartoonist" from RACONTEUR #3.
You can order #3 at the link, or get all four issues that came out in 2012 at a reduced price here.