Some shoes have really slippery soles. Even in dry conditions, walking in shoes like this can be a dangerous adventure. If you have a pair of shoes with slippery soles, don't throw them away yet. Get some of the non-slip decals that you can buy for use in bathtubs and showers. Cut out some pieces so that they'll fit on the soles of your shoes, and stick them on (they stick a lot better if you clean off the soles first and let them dry). I did this on a pair of shoes with leather soles. The shoes were previously unwearable since they were so slippery. But after adding the non-slip stickers, they were great. Saved me a ton of money on new shoes.