Halloween is the perfect time to revisit the fascinating figure of Harry Houdini, who died on October 31st in 1926. The Library of Congress has assembled an outstanding selection of articles about Houdini's penchant for debunking spiritualists from newspapers of the time. They're worth perusing for the ads alone, but also for stories like this one from the July 1, 1922 edition of the Ocala Evening Star.
Houdini's point in fooling Roosevelt was to illustrate that if he could get one over on a room full of intelligent, worldly men, small wonder that skilled spiritualists could fool an audience who came in wanting to believe.
The Library of Congress has even assembled a selection of Houdini's column in The Washington Times where he would respond to readers' questions about psychic phenomena. One gentleman, for example, was astounded when a medium could tell him various aspects of his life, like his name, family members, and other "facts connected with my life which were all true." Rattled, he was hoping Houdini could explain what happened, a favor the master was more than happy to grant.
Houdini goes on at length about the many, many methods mediums employed to appear to be in touch with know-it-all spirits. It's clear that his goal is to not to make the duped feel foolish, but rather to protect them against future attempts to part them from their cash. Houdini had no time for fakers, and watching him take them apart is still great a hundred years later.
The post on the Library of Congress site about Houdini is intended to provide guidance for teachers, but dig into its links and you'll find a marvelous collection of first-hand stories.