Everyone knows that when you draw a character talking, they should always have their mouth open, right? Well, as I've been drawing more and more and coloring in those drawings with colored pencils, I've become aware of a problem I can't seem to come up with a satisfactory solution for.
Specifically, what color should an open mouth be?
There's no problem with black and white, of course, or if the expression of the open mouth is a smile or gritted teeth, in which case I'd just leave it white to suggest the teeth. But what if it's a non-tooth-y open-mouthed expression?
Should the open mouth be black, to indicate the shadow that would exist if you're looking at an open mouth from a certain distance? (Like, looking at my self in the mirror making one of those expressions, it looks black). Or red or pink-ish, because that's what color the insides of mouths are? (It's not like I draw any other shadows, after all). Or should the mouth just be left un-colored...or perhaps colored in, the same color as the rest of the head...?
I can't decide which looks best/least-bad.
Your input would be appreciated.