In New England we do it in the Fall on wet leaves. They do however seem to be more visable in their international safety orange vests.
Scary is realizing that your doing 17/18 mph on a 3 foot wide dirt path with trees on one side and a dropoff on the other with an unknown thickness of leaves under tire. Its like driving a bit too fast on snow and ice (sorry california folks, thats white solid water that.........well, you've got the Mighty Ducks so maybe you know). Everything will be alright if nothing goes wrong.