Usually it's nowhere near as bad as it has been and dries up within a few hours to a day so I don't worry about it.
It's wood shavings you can get at TSC.
We've had horrible rain the past few days, and I have just gotten home for the night to see someone has spread bedding out in my chicken run to try and soak up the mud. While I appreciate the gesture, I am worried because the bedding was already wet of the rain, and rain we had days/weeks...