Did you see that note in your link that red food coloring, for instance, could produce red fog? Quite awhile ago, I tried that for smoke liquid. Food coloring is nothing but colored propylene glycol. It smokes fine. I envisioned snorting red vapor from each nostril! Or puffing green vapor at an environmental group's meeting.
Ooooooo. Failed experiment.
The food coloring colored everything it touched: atomizer, inside of the e-cig, cartridge and core, and .. my teeth. My whole mouth looked like a nine-year-old's after eating a cherry snow cone.
Bottom line: Red teeth are not funny to the mouth displaying them.