OK, I could very well be wrong. May I ask, is it the only meaning of the word mentioned, or the main one? Someone else who has a good book to check? Words often have several meanings... the word is often used as an insult, carrying negative connotations. On that I hope we can agree.

Certainly. And the word "quackery" is negative because the phenomenon it describes is negative like, say, "vandalism".

It looks to me that you actuallly want to use it for this very purpose - to warn the readers i.e. you decide what people should be warned of. Maybe I want to warn people for religion - can I create [[Category:Unscientific supernatural beliefs]] and put [[Christianity]] in it?

Fine by me. And wouldn't most Christians agree that their religion is a collection of unscientific supernatural beliefs?

During the course in oncology, our teachers told us that many of their patients also sought for some alternative method of various kinds. They were not at all against it - they said the alternative people gave the patients something they badly needed, both for better prognosis and for quality of life - often not a very long period of time. That thing the alt.med. stuff can give in that situation, is hope...

Sure, how about [[Category:Comforting lies]]?

and I still can not see that you have explained wherein the usefulness of this particular category lies.

What's the usefulness of any category? It's mostly an aid to browsing, I suppose. You're reading about one thing and maybe you'd like to read about other similar things.

You're right that the category shouldn't be a primary warning label. The article itself should make clear the efficacy of its subject (or lack thereof). On the other hand I'm arguing that upholding a distinction between quackery and alternative medicine in the category system is misleading.

Regards, Haukur

P.S. I hope I'm not getting too worked up about this. I haven't actually edited much in the quackery field in the past, I mostly work on Norse mythology. In that field I frequently see categories used to claim something not actually supported by the article.