In a 2019 television segment on Last Week Tonight featuring prominent purported mediums including Theresa Caputo, John Edward, Tyler Henry, and Sylvia Browne, John Oliver criticized the media for promoting mediums because this exposure convinces viewers that such powers are real, and so enable neighborhood mediums to prey on grieving families. Oliver said "...when psychic abilities are presented as authentic, it emboldens a vast underworld of unscrupulous vultures, more than happy to make money by offering an open line to the afterlife, as well as many other bullshit services."
After her death in the 1980s the medium Doris Stokes was accused of fraud, by author and investigator Ian Wilson. Wilson stated that Mrs Stokes planted specific people in her audience and did prior research into her sitters. Rita Goold a physical medium during the 1980s was accused of fraud, by the psychical researcher Tony Cornell. He claimed she would dress up as the spirits in her séances and would play music during them which provided cover for her to change clothes.
In 1910 at a séance in Grenoble, France the apport medium Charles Bailey produced two live birds in the séance room. Bailey was unaware that the dealer he had bought the birds from was present in the séance and he was exposed as a fraud. The psychical researcher Eric Dingwall observed the medium Bert Reese in New York and claimed to have discovered his billet reading tricks. The most detailed account at exposing his tricks (with diagrams) was by the magician Theodore Annemann. https://drive.google.com/file/d/1NC_exEwvIecJ9EWDa-MwzzZdzPkWWZ-H/view?usp=sharing
Senses used by mental mediums are sometimes defined differently from in other paranormal fields. A medium is said to have psychic abilities but not all psychics function as mediums. The term clairvoyance, for instance, may include seeing spirit and visions instilled by the spirit world. The Parapsychological Association defines "clairvoyance" as information derived directly from an external physical source.