Do e-liquids contain sugar?
Not like the granulated sugar in your coffee. The sweet sensation comes from the VG itself or additives like sucralose. You won't get cavities from vaping, but your coils might not appreciate the special treatment in the long run.
E-liquids use sweeteners. These molecules are stable under heat but eventually caramelize on the resistive wire. This black gunk is what eventually causes a burnt taste. The sweeter the liquid, the shorter your coil's lifespan.