Unreliable source

[Luis Fok]

[Unreliable Source] is a common tag used by Wikipedia. Wikipedia is (or intended to be) a open source encyclopedia.

In theory, the tag [Unreliable source] is used when an article or part of a article [cite] or talk about some [questionable content].

But, in a real world scenario, Unreliable source is used as a form to piss off contributors. Even by using logic, if a statement is correct but some editor consider to screw it, then it can claim that the statement is incorrect.