For the most part, zero. Mainly because they are worded in an extreme fashion which makes them very easy to dismiss. Some are utterly idiotic, like the 300 pound commentary, which frankly isn't even worth "proving" wrong because everyone with a functional brain realizes it is not the case.
It is like taking the rants of an angry person and expecting them to be logical. It is not going to happen. A lot of fans are angry because they are disappointed. They don't "hate", but yes, their disappointment is evident and comes out in the form of frustration. Specifically at the player because they have seen better and expect more.
Just because they are not "factual" and articulate in their verbiage doesn't dismiss any sliver of truth in what they might have to say. You can spend a lot of time sifting through that commentary and come up with myths and inaccuracies, which is obviously something you have devoted quite of bit of time doing. But that doesn't disprove a single solitary thing.
Overall, the average person speaks in general terms. If they don't like what a player does on a consistent basis, they "suck". In Williams' case, he "can't cover" when he blows assignments. No, not a single person on this message board looks at every single snap and focuses on Roy Williams and dissects his play unless you are a coach and have access to the coaching tapes.