The term mountebank is derived from the Italian, montembanco, which refers to someone who gets up on a bench. Simply put, a mountebank is a peddler, particularly of bogus medicine. In closer association to its Italian derivative montembanco, the term mountebank refers to someone who sells bogus or quack medicine by standing on a pedestal or platform to address and entice an audience of potential quack medicine buyers.
A mountebank is someone who sells by means of deception, who dupes a customer into purchasing a good. Although the term originally pertains to someone who sells dubious medicines, it can also refer more generally to anyone who resorts to spectacle in order to attract buyers. A mountebank could be anyone who participates in flamboyant spectacle, trickery or pretense to obtain an advantage, especially monetary advantage.
Other synonymous names for such a person include charlatan and con artist. More specifically, a charlatan is a boastful pretender of knowledge or skill. In the same sense, a mountebank is someone whose means of beguiling their customer usually takes the form of some pretended knowledge, false knowledge which the potential buyer, presumably, does not share.
It should be understood that, according to original indication, a mountebank does not force his goods on a buyer. Nor does he generally fool a buyer into purchasing something by means of some grand and elaborate scheme. Rather, a mountebank plays upon the desires of people to ascertain the mysterious. A mountebank exploits someone's desire to know what few others know, and to thereby become part of the few.
The quintessential mountebank employs exclusivity and exoticism to attract his customers, and to make them want what he peddles. In this sense, the term mountebank can be applied to anyone who dupes a customer by means of feigning access to the inaccessible, and offering that access to the average person for a price. Within this connotation, one could consider palm readers, psychics, tarot card readers, and spiritual communicators to be species of mountebanks.
This is, of course, a view that would be held by a skeptic of what these people claim to offer their customers. The term mountebank expresses a negative connotation, and refers specifically to someone whose goods and services are untrustworthy and fabricated. Mountebank is a subjective term, a term that applies a qualitative judgment. A skeptic might, therefore, describe anyone who claims to have access, appropriate treatment, or a solution that the skeptic does not trust, as a mountebank.