It always sounded pejorative to me, but "wicked stepmother" is apparently a label she wears with pride. This is from one time when she caught her stepdaughter and her boyfriend in her room doing something that she'd clearly told them would not be tolerated under her roof.

I told the young lovers, truthfully, that they never looked a cuter couple than they did while staring into each other's teary eyes in agony and sorrow while dancing around the room and clutching their bare and red hot bottoms. They weren't very appreciative of this. What a couple of brats.