These are lightweight, quick-drying waraji-style sandals made by wrapping nylon cores with new bean-patterned hand towels and then braiding them. The black color visible on the upper right foot is not dirt or a stain; it's part of the black polka dot pattern. They are softer than cotton, so they may wear out more easily, but they feel good against the skin. Size M, recommended for those with feet around 23-23.5cm. Hand wash and put in a net for spin-drying, or use the delicate cycle in a washing machine with a net. If they feel too tight or loose while wearing, untie and retie the thong on the underside. Please understand that these are handmade and not perfect. Please refrain from purchasing if you have a dog allergy.