quack

A pseudomedical "professional" who earnestly believes in their products or procedures (as opposed to a fraud, who knows he is full of shit and just wants to make money), which in actuality are of dubious merit and are possibly injurious.

(Name) the quack (my chiropractor)
Was a squat little ape
With a mouse's voice
And a pigeon's gait

by Anon343 March 16, 2008