I think it is a form of detox that occurs on a very deep level. When I was doing The Master Cleanse I had several incidents where I could taste foods I had not eaten in years. In one cleanse I could smell cigarette smoke after a bowel movement. I never smoked either, but have been around it quite often. However, when I was doing the cleanse I was housebound from a back injury and had not been anywhere near cigarette smoke in months.