I agree that saying "you're wrong" isn't an effective rhetorical technique, but trying to argue with alt-right trolls is a waste of effort.
Sites like Snopes and Politifact do the research, with primary sources, to actually validate claims. Since conservatives can't actually invalidate those claims, they've decided to simply claim that any source which disagrees with them is biased.
The evidence is often correct. It's the assignment of weight to each claim, lack of charity when reading, and therefore output of the truth-o-meter which is biased. This isn't just rhetoric; it can be evaluated rationally.
Worth scrolling through this Twitter feed [0] for individual examples. They can be validated and many are not just 'gaslighting by the right'. And others feel this way, too [1].
To some extent, I agree that Politifact's ratings are bad because they're inherently subjective. Thankfully Facebook's system will allow you to click through to the original article and read the evidence for yourself.
The latest claim is that even Snopes is politically motivated and lying. The amount of gas lighting which the alt-right is doing is absurd.
Sites like Snopes and Politifact do the research, with primary sources, to actually validate claims. Since conservatives can't actually invalidate those claims, they've decided to simply claim that any source which disagrees with them is biased.
It's gaslighting.