Don't you hate it when........

Yeah, it's so frickin annoying! XD

I saw Ms. Bellums face when I was little in a PPG book. Her whole face. She just looked like what I expected her.

If they do that, it's a running gag intentionally put there and it kinda helps... depict the character in a way...
So no, not really.

And ooo, I know another example! Of a cartoon character whose face is really never shown: Kelly Wizard from The Proud Family.
And another character from a live sitcom whose full face is never showed (usually, a fraction of it is shown but never the whole thing): Wilson Wilson Jr. from tahanan Improvement.

WHAT
how dare you forget the episode
now im mad
?
did she luk good or was she ugly

Yes!

LOL, like the parents of the earlier Fairly Odd Parents? X-D

Neh, I already saw Miss Bellum's face. The only faces I couldn't see is the face of Mammy Two Shoes in Tom and Jerry. I don't know if they ipakita it already.