Random House Dictionary describes a "quack" as a "fraudulent or ignorant pretender to medical skill" or "a person who pretends, professionally or publicly, to have skill, knowledge, or qualifications he or she does not possess; a charlatan".

The late Stephen Jay Gould offered a synopsis of the mainstream response to Velikovsky, writing, "Velikovsky is neither crank nor charlatan—although, to state my opinion and to quote one of my colleagues, he is at least gloriously wrong...

When the 1996 version of 'The Mismeasure of Man' came and he never even bothered to mention Michael's study, I just felt he was a charlatan."

One short story "Trulku" was criticized for its portrayal of a charlatan lama who goes onto have relationship with two women, this caused a furore in the conservative Tibetan community in Tibet.

In 2010 Rabbi Abuhatzeira was accused by New York Jews of charging hundreds of thousands of dollars in exchange promised miracles that never came to fruition The prosecutor in Brooklyn subsequently opened an investigation, and Abuhatzeira stopped traveling to the United States as a result. Yossi Bar Moha, the journalist who investigated the Rabbi in 1997, claimed that "Elazar Abuhatzeira is a charlatan, con man and impostor who takes advantage of people's innocence, exploits them and brings to the verge of poverty".