While it is impossible to prove conclusively that no one has ever had true psychic abilities, such abilities have never been demonstrated in credible, repeatable laboratory experiments. Psychic powers, such as mind reading and remote viewing, are at odds with what science says should be possible.
Many people claim to have psychic abilities, but there is no reliable way to distinguish actual extra-sensory perception from random chance or heightened intuition. HowStuffWorks points out that people give off subtle clues through body language and facial expressions that can tell a perceptive observer what they are thinking about. A skilled psychic practitioner can use those clues and other techniques to convince a client that he has real psychic abilities. Many people, particularly those seeking help, want to believe those powers exist, so they are easier to convince.