I never saw Donna Murphy's Anna, but the Forbidden Broadway spoof of that production will eternally live in my mind (They had the actress playing Fosca-as-Anna, complete with huge mole, and sang "Shall we Boink?" lampooning the production's apparent oversexed subthemes, while throwing in a "La Bamba" reference or two.)
I don't know the roles well enough to do these "worst cast" things, but Carol Channing's Anna would be one that would scare me...