Scale rot is also caused when a snake is unable to shed its skin which adheses the old skin onto their new clothes and nothing is done about it. Each time a shed cycle comes round, the same thing happens. In this case, scale rot can actually be completely invisible because it is hiding underneath multiple layers of skins. So to prevent this happening, keep your husbandry standards up to scratch and be sure your snake does shed its skin, and all of it. Small amounts of retained skin left on them isn't usually a problem. Quite often it will come off next time round, but when snakes are kept too dry, too hot, too cold, this can, will and does cause issues with their shedding which in longterm will lead to scale rot.