A very large part is played by fraud in spiritualistic practices, both in the physical and psychical, or automatic, phenomena, but especially in the former. The frequency with which mediums have been convicted of fraud has, indeed, induced many people to abandon the study of psychical research, judging the whole bulk of the phenomena to be fraudulently produced.
I was 13 when my mom dragged my brother and me to a "psychic." We were visiting family in Malaysia and somewhere amongst a few palm oil plantations was the house of an old woman who claimed to be able to channel Buddha. My mother was enthralled during the hour-long ordeal, during which the woman basically rolled her eyes often so the whites were showing, dropped her voice a few octaves, and made astonishingly mundane statements that could've applied to anyone (examples: our house had ants out front; my grandma was old and having some health problems). Combined with my love of Harry Houdini (who spent the last few years of his life debunking psychics and mediums) and teen angst that made me hate everything my parents liked, the experience left me convinced that psychics were con artists who separated vulnerable and desperate people from their cash in exchange for poor acting.
I'd heard about the job through a friend of mine, who worked in Human Resources for one of the most prominent phone psychic companies in the world. She knew that I'd learned to read tarot in college and that I often booked events and comedy clubs. Sometimes I was accurate, but mostly, I was entertaining. Once, at a New York Fashion Week party in SoHo, I read the cards for a nonbeliever who edited what many fancy fashion folk refer to as "the Bible." He was making fun of me when I leaned in and whispered, "Don't cheat on your wife."
Many 19th century mediums were discovered to be engaged in fraud. While advocates of mediumship claim that their experiences are genuine, the Encyclopædia Britannica article on spiritualism notes in reference to a case in the 19th century that "...one by one, the Spiritualist mediums were discovered to be engaged in fraud, sometimes employing the techniques of stage magicians in their attempts to convince people of their clairvoyant powers." The article also notes that "the exposure of widespread fraud within the spiritualist movement severely damaged its reputation and pushed it to the fringes of society in the United States."