In a nutshell: Channeling dead spirits was popular in the 1980s. The Australia tv show 60 Minutes hired James Randi, famous skeptic and magician, to create a fake channeler to see if the public swallowed it.
He made up a fake bio for his student, including fake public appearances in many cities. He issued press releases and the media swallowed the story hook, line, and sinker. They ran the story without even verifying it.
Later when the channeler revealed his ruse, he received letters saying, "Don't listen to the media. We still believe in you." 8-