Not my boys. The dirtier, muddier, and wetter the better.
Clean up? No problem, half the time I find their discarded clothing (my littler ones that is) because if the clothes got too dirty or too wet to impede exploration or play, they just toss the offending article off to the side. This has led to many a laugh when mom is gardening and in the toss of a shovel of dirt I will turn only to find a partially or totally nude toddler running across the grass. There I go chasing boys again, at least trying to civilize and clothe them.
I think at its root little boys need to get dirty because they need to explore. They need to see how things work, they need to dig in the dirt, they need to look under rocks, they need to conquer the great outdoors, or at least leave a valiant effort in their wake while trying.
I also think that little boys are better for the ability to be able to get dirty. I once had a friend who never allowed her son to get dirty. He always had the cutest clothes, the nicest shoes, but frankly...I felt so sorry for him. He wasn't allowed to get dirty.