CNN  —  Mong Shuan was just 16 when she turned to an unconventional source of income: selling betel nuts from a little stall in northern Taiwan . The stimulant, a small, oblong fruit derived from areca palms, is chewed by millions of people across Asia. For the next three years, Mong would work six days a week for the equivalent of around $670 a month. A small bonus was tacked on for dressing provocatively to entice male customers. Her job was to slice the nuts open and add a pinch of slaked