The charlatan is usually a salesperson of a certain service or product, who does not try to create a personal relationship with his "marks" (the persons to whom the service or product is sold), or set up an elaborate hoax or con game using roleplaying. Rather, the person called a charlatan is being accused of resorting to quackery, pseudoscience, or some knowingly employed bogus means of impressing people in order to swindle his victims by selling them worthless nostrums and similar goods or services that will not deliver on the promises made for them. One example of a charlatan is a 19th-century medicine show operator, who has long since left town by the time the people who bought his "snake oil" or similarly named "cure-all" tonic realize that it does not perform as advertised.