Alan is exactly right about the semantics of "cult" and "brainwashing." The denotations of these words pretty much do the job of describing Witnesses, but their connotations don't always -- and so these words are understandably too distracting to be productive, at least in any discussion with Witnesses. Of course, the phrase "discussion with Witnesses" is sort of an oxymoron, at least if the word "discussion" means anything.
Anyway, I guess my parents tried to brainwash me (read: "inculcate the troof in me"), but it didn't work.
Dedalus