Like Alec, I'm a big fan of mistaken identity, role reversal, identity-swap/theft, and social demotion (which includes age-regression to the status of a child). Spanking can be an important component in the story, as a means of demotion and humiliation, but it is not the
primary focus of interest for me. Adults mistaken for, or demoted to, school-kids, ladies and maids, executives and office cleaners, and and pretty much any other "status pairings" can all be good.
alecleamus:
There must be a feeling of her being trapped. It is especially enjoyable when they reveal their true identity and no one believes them in their current attire or state.
I could not have put it better myself.
I'm a new member here. Is it within the rules to post links to stories on other sites? I can think of a couple of examples that might meet the OP's requirements.