for your information, recent studies have shown that showering greatly reduces the build up of both oils and salts on the surface of the skin.
serious cyclers will prefer to allow these to accumulate. the oil build up decreases the aerodynamic profile by creating a slicker air/body surface interface.
additional benefits derive from the prefered method of removal. during a race or long distance tour, the in-the-know cyclist will lick themselves, providing high caloric fat intake for extra energy, and also replacing lost electrolytes, thereby enhancing muscular function.
brushing your tongue will enhance absoption of both fat and oil. however, as noted by others, one must take pains to avoid brushing the teeth themselves.