People are idiots?
She gets called it because some say she was brought in to 'prove' to Jorja and George after the firing thing that they were replaceable. Plus, she flirting with Grissom. Big whoop. People can't just cope with the fact she's a good character, and can't get past the flirtation with Grissom.
It's such a childish nickname to call her. Really winds me up. (And for the record, i'm a huge Sara/Grissom and Jorja Fox fan too)