a person who sells quack medicines, as from a platform in public places, attracting and influencing an audience by tricks, storytelling, etc.

any charlatan or quack.

to act or operate as a mountebank.

noun

cheat , con man/woman , grifter , imposter , rip-off artist , swindler , charlatan , faker , fraud , humbug , impostor , phony , pretender , quack , empiric , hawker , hustler