[In response to, "Of course, this raises the question of why the other Cullens don't make judicious use of blush or foundation to disguise their corpse-like pallor."]
Or contact lenses to hide their mood ring eyes. It would be easy enough for them to appear to have eyes that were brown or green or blue. Instead they seem to be going for, "Look at me, I'm not normal."
"Your eyes are black as coal."
"That's not good, hang on a moment." (Goes away, returns.)
"Now your eyes are the color of petrified tree resin."
"That's called amber, just so you know."
"Hey, where's my horse?"