Instead of sticking a hand into a deep dark place, many geocachers carry a walking stick and use the stick to move things around. Let the snake bite the walking stick and not the hand! If you have to use your hand, some people bring gloves with them for just the occassion. One trick to GeoJim taught me was that instead of sticking your hand into the hollow of a tree and blindly feeling around, you take a flash picture with a digital camera and then look at the picture.