Here is example of PolitiFact bias:
Clinton Says Donald Trump "used undocumented labor to build the Trump Tower."
So, that's what Clinton said. Then the headline right after that on PolitiFact says: Hillary Clinton correctly claims that Trump Tower was in part built by undocumented workers.
Also says Rubio said similar thing, and they gave him lower rating (I think Half True) because of how specific he got.
And PolitFact concludes with:
Clinton claimed that Trump "used undocumented labor to build the Trump Tower."
There’s no question that undocumented workers were hired to do demolition work on the future site of Trump Tower. Questions remain as to how involved Trump was in the construction process and hiring of the 200 Polish laborers, but Clinton is factually correct to say that undocumented labor helped construct Trump’s New York skyscraper.
We rate this statement as True.
So, score another one up for Camp Clinton as "True" when given everything stated here, and linked from here, strikes me as certainly not clear Trump knew they were on the job, nor did he directly hire them. But it is attributed to Trump and also not attributed to him, to allow for wiggle room.
Me, I'd go with Half True.
Guessing if only LW types respond to this post, they go with Mostly True or higher. Guessing if I put same type of thing up for discussion in "Conservatives Only" and/or if Conservatives on the site respond to this post they go with something lower than "True." Feel another fact check site would rate it differently than PolitiFact, though admittedly not sure.
But what I'm saying is this stuff adds up, and Clinton gets a "True" in her column based on what is a very questionable rating. If this stuff didn't add up, and this was the only item PolitiFact rated, I'd say teeny tiny/negligible bias. But I'm saying if I did this same type of thing for say another 10 posts (that I'd pick), it would lead to similar conclusions of it being (highly) questionable, how they rated. Thus, to be fair, we can strip off around 30 or so of the True assertions from Clinton side, and perhaps add about 50 or so from the Mostly True and Half True side to the Mostly False side, ya know, to get a more accurate picture.
Not to mention the dozens of things they don't choose to take up about what Hillary says.