It is possible to provide arguments against the reliability of any source whatever. (And in the other direction, it is possible to take most sources and selectively quote them to provide evidence for support for any position whatever.) It is possible to destroy the integrity of any article by concentrating on finding weaknesses in the sourcing combined with careful use of sources that appear reliable, but are not really to the point. Even a single person doing this can work havoc, and if this is done in a concerted way, it provides ample scope for the expression of bias. The cruder forms of this technique are of course widespread in politics--they tend not to work well in Wikipedia, but slightly more sophisticated use of the method can be quite successful unless the opposition is equally determined.
Conventional advice that we can can deal with this by applying NPOV do not solve practical problems, for the question of what is neutral and what is balanced and what is fringe are always to a considerable extent matters of opinion. Neither do comments that we can deal with everything by applying BLP strictly, for not only do most articles on contemporary topics to some measure involve BLP, but in any case this simply shifts the argument to what falls within the BLP rules. If you move the goalposts, the arguments will follow. Wikipedia is written by humans, & the assumption that the individual prejudices will always cancel each other is easily falsifiable.
This has been seen outside of politics. The two currently pending requests for arbitration both deal with this type of sourcing problem as the underlying issue. In my own view, they are both tending towards inequitable resolutions.
In the arbitration cases I was in involved with that were similar I made heavy use of the formulation, "editorial judgment" which requires editors to be responsible and to use some sophistication rather than buying into "for the question of what is neutral and what is balanced and what is fringe are always to a considerable extent matters of opinion." In other words, to act in much the same way a professional editor does; be a hero...
Where this falls down is in cases like the Kochs, or indeed in the case of macaroni and cheese; these are not burning issues which command intense attention by skilled editors. Anyone who votes against their own interests or eats food that is not good for them gets what they deserve; WP:BEANS
"Don't be an idiot" is not a viable policy formulation for Wikipedia or in life.
Fred