I don't think her vocal abilities should come into question for Charity. Sure, she's not a WONDERFUL singer, but - call me crazy - I thought she was charming, spunky, and funny in ONCE UPON A MATTRESS.
I don't think she can dance, though, which is what you need for Charity.
Well, I suppose in SWEET CHARITY when not choreographed by Wayne Cilento...
"If you are going to do something, do it well. And leave something witchy."
-Charlie Manson