All leather products can not be washed in any case. If you get one part of leather harness dirty (Make Up, Deo, Glitter etc.) so you can apply little bit of body cream without perfume, preservatives and alcohol on top of the leather and gently wipe with a dry cloth or cotton pads without to pull the leather.
The Leather Belts should hang on a hanger. If a part (a part from soft leather) is wrinkled, you can even iron from the inside with a dry cloth slight to medium heat (with pressure without pulling the leather).
If the purchased item has a too long harness, you can cut the belt, depending on the personal size.
By leather scurf failure a lighter can help, gently and quickly heat up short at the edge of the leather from the inside.