Definitions of charlatan on the Web (http://www.google.com/search?hl=en&q=define%3Acharlatan):
(char?·la?·tan) (shahr??l[schwa]-t[schwa]n) [Fr.] a pretender to knowledge or skills that he does not possess; in medicine, a quack.
mountebank: a flamboyant deceiver; one who attracts customers with tricks or jokes
wordnet.princeton.edu/perl/webwn
A charlatan is a person practicing quackery or some similar confidence trick in order to obtain money or advantage by false pretenses. If the ascription is false, then "charlatan" is pejorative; if it is true, then the description "charlatan" is no libel.
en.wikipedia.org/wiki/Charlatan