The word comes from French charlatan, a version of "Charley," a seller of medicines who might advertise his presence with music and an outdoor stage show. Ultimately, etymologists trace "charlatan" from either the Italian ciarlare, to prattle; or from Cerretano, a resident of Cerreto, a town that was apparently notorious for producing quacks.
A famous American charlatan was John R. Brinkley, the "goat-gland doctor" who implanted goat glands as a means of curing male impotence, helped pioneer both American and Mexican radio broadcasting, and twice ran unsuccessfully for governor of Kansas.
 Subtle definitions
In usage, a subtle difference is drawn between the charlatan and other kinds of confidence people. The charlatan is usually a salesperson. He does not try to create a personal relationship with his marks, or set up an elaborate hoax 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. The aim is the same, however: to swindle his victims by selling them worthless nostrums, and similar goods or services, that will not deliver on the promises made for them. The word calls forth the image of an old-time medicine show operator, who has long left town by the time the people who bought his snake oil tonic realize that it does not perform as advertised.
 Legal implications
Because of the connotations about intentional deceit, calling someone a "charlatan" can actually be libelous or slanderous. Therefore, even with mounting evidence in support it can be a dicey thing to just call someone out as a charlatan scam artist. So it's not advisable to call people like Peter Popoff, Jim McCormick or Harold Camping, or Deepak Chopra, or Danie Krugel... or Jerome Corsi "charlatans". Indeed, Simon Singh got into a very expensive lawsuit after using the word "bogus" in an article about chiropractic medicine - even though he was later vindicated. These people totally aren't charlatans for what they peddle, by the way, they're just there for illustration and it's just a co-incidence that people like Mehmet Oz, Gary Null and the Geier family are being used as examples of people who definitely are not charlatans.
However, as noted by Penn and Teller in their first episode of Bullshit!, while accusations of running scams and calling people charlatans can dump you in the lingering boiling oil and melted lead of the legal system, calling such people "bullshit-merchant assholes" is perfectly fine.
 See also
- See who? There's no one mentioned on RW that we would imply were charlatans! My, such an accusation is unfounded!