If we think back to the time May accidentally ripped her face skin off, we'll see that humanoid AIs in the QC-verse, even ones in janky, low-rent government issue chassis, have very elaborate facial myomers that closely mimic human facial muscles.
The rest of May's body is basically abstract blue plastic (she was shirtless during the repairs, and was, uh, even more featureless than a Barbie doll), but her face and the ability to make expressions is the one thing that works well.
From this, I'd deduce that facial expressions in AIs are very, VERY well developed, and the colorful dermals might help erase the last of the uncanny valley effect. Plus, if people could choose skin colors, why wouldn't many of them choose something bright or bold?
Momo is the one character we've seen who has life-like translucent caucasian skin, and she's been mistaken for a human more than once. Even so, she still has pink hair and "big ol' anime eyes".
Humans (and AIs) are VERY good at reading expressions and body language, so facial myomers aren't really necessary to be understood. Several characters have more abstract faces (Pintsize, O'Malley, Punchbot, Arthur, Swordsmary, "Punkbot" - does he have a name?, etc.) with varying degrees of mobility and features.
Interesting stuff to think about.
So anyway, where's this week's Overthinkers Anonymous meeting? Down the hall and to the left?