Wikipedia:Cite tendentious texts directly
Wikipedia already requires verifiability (WP:V and WP:OR) and a neutral point of view (WP:NPOV), but it seems that in order to lay a claim to objectivity, Wikipedia must also require source citations to be treated differently according as whether the substance of the text is indifferent (i.e. cannot spark an argument among the majority of readers) or tendentious. It is not fair to readers to cite tendentious texts indirectly--that is, by paraphrasing or summarizing the content, because that is the way in which certain authors with personal agendas try to influence the content of an article.
As such, any text which takes a side on a difficult or controversial question--especially in cases where the text represents an extreme viewpoint--should be cited directly.
Contextualize tendentious texts
In addition to citing tendentious and "extreme minority point of view" texts directly, Wikipedia editors should also contextualize these texts by setting out how the most reputable sources view these tendentious texts. For example, if the vast majority of reputable sources assert that there is no life on Mars and an article in a single journal by Dr. Krunk claims that there are Martian lifeforms, readers should not be given the incorrect impression that there is a "50/50" split of opinion on this issue. Clearly state that the majority of reputable sources assert that there is no life on Mars, and indicate that a single reputable scholarly source takes the opposing view.