I don't have any pics but I had a chestnut mare once that really wanted to be a gray. I had this mare in Louisiana and the dirt there is literally dark gray. This mare, even after no rain for weeks, would find mud, which looked like wet cement, and just cover herself in it..belly, ears, face, everything. Her favorite time to go out, of course, was right after a good soaking rain..all that lovely gray mud to roll around in. I gave up ever brushing it out. It was pretty much standard practice to just hose her off and watch the color transformation.