I have spot cleaned mud off of mine with baby wipes- it was only semi-successful. I have not washed them in the washer or anything. Beware, these are not waterproof, so you definitely might get water and mud on your socks if it is wet enough in the cave. I had to walk through some really thick, gross, wet mud after the spring thaw- an emergency so I couldn't walk around it- and my feet got wet and muddy.
I haven't had them in mud, so don't know how well they wash up. Am guessing they wash up ok. hey are great hiking shoes though. Are wide enough to get a variety of sock weights under them. I bought my normal shoe size.