I had a thoroughly enjoyable run on Saturday, the return leg of which involved the unclassified roads between Darvel and Eaglesham. Virtually every farm, and there were many, that I passed had muck on the road to some extent, some a lot worse than others, but the work was ongoing and the driver of each of the tractors I encountered was courteous and gave me as much road room as possible. For my part, I slowed right down when the mud was significant.
Yes, my bike and I were both manky when I got home, but I can't really get excited about it. Although I live in a city now, that wasn't always the case and I'm aware that farmers have to work according to the weather rather than the clock, so often, and particularly with the weather this year, they have a very limited window of opportunity to get various tasks done. As others have mentioned here, it simply would not be practical for them to clean as they go, and in the short term, would probably make things worse.
Live and let live.