Activities and processes based on chemistry and hucksterism that form the basis of one of the most profitable businesses in the Western industrialized world.
The ideal market, briefly defined, is one that is never saturated and that will bear inflated prices. (One is tempted to add that the product must also be unnecessary in any practical sense.) Many consumables paper, photographic film and paper, seeds, and so forth satisfy the first of those conditions but not the second (or third). Supplies for beauty treatments satisfy all.