Teddy, I know how you like to keep yourself white and clean and that’s good because this is what the Cambridge dictionary says about cleanliness. The definition is “being clean or the act of keeping things clean.”
Combing your nice clean hair with an unclean icky hair brush is almost like not shampooing at all. With each stroke, you are dragging oils, odor and other gunk through your hair. It is important to always use a clean hairbrush.