More broadly, they should never be shaped like a living thing.
I recently attended a party where this poor thing was beaten to a pulp:
First, her dainty little feet were bashed clean off. Then her neck began to go, ever so slowly, until her smiling face was facing backwards while the rest of her faced forward. All the while the smile on her face remained unmarred as she literally fell to pieces. Things went from bad to worse when the kids began taunting her; "You wanna piece of me?" "Here's a piece of me." WHACK. As though she had done something to offend them! {I am pleased to report that Caelah seemed overwhelmed by the over-enthusiasm the other kids were exhibiting, and seemed more fixated on the candy than the wounded fairy.}
No. Nothing with a face should have it's likeness made into a pinata.
