Deeanne Gist stood in a packed hotel conference room wearing nothing but her underwear.

For most people, giving a presentation in skivvies to 100 professional peers sounds like a bad dream. But Ms. Gist was giving a workshop on Victorian clothing at the Romance Writers of America's annual convention this summer. The romance novelists had gathered in New York to learn how to dress—and undress—heroines in their novels.

It...