After washing off the dirt and bugs, I'll go over it again with a "Magic Eraser" and a towel, rung-out wet with a mixture of 8 to 1 simple green and water. It takes off everything with medium to light effort.
Each time I do this, it gets a little easier, because I will also wax a portion of the outer skin each time I wash it. After a season of use, the whole rig has been waxed. Yeah sure, I could do it all at once, but like I said on another post today " We learn my our mistakes"