Most hated character?
Joanne Forbes, the lady that accidentally hit Mary's car, developing into a brief friendship. It's similar to "The Golden Girls" episode with Barbara Thorndyke, although Janne didn't always exhibit a snobbish personality. It made me proud of Mary when she tests Joanne by telling her she's Jewish to see her reaction. Joanne's reaction says it all to Mary, being the nice person she is, yet wisely ends the friendship fast.
And, Mary wasn't looking to butter up to Rhoda being she never told her about this.