PolitiFact has a Lean Left bias.
Fact checking sites often display bias because selecting what gets fact-checked and how it will be checked is subjective in nature. Independent reviews by AllSides has found that Politifact's bias is Lean Left.
In July 2018, 18% of Politifact's "fact" checks were actually checks of opinions, reports Investor's Business Daily, citing RealClearPolitics' Fact Check Review (a site that fact checks fact checkers).
In widely-criticized piece published April 2016, Politifact said it is false to describe a person by their biological sex if that person identifies with another sex. Assessing a presidential campaign ad by Ted Cruz, Politifact wrote that “it’s not accurate to say that transgender women are men.” Following criticism, the website issued an editor's note and then changed the article to state, "“it’s not entirely accurate for Cruz to define a transgender woman as ‘a grown man pretending to be a woman.’”
A Capital Research Center piece about "Dishonest Fact Checkers" claims, "A Media Research Center analysis in June found that Trump received the “False”/“Mostly False”/ “Pants on Fire” label from PolitiFact’s Truth-O-Meter 77 percent of the time. Clinton received just “False”/“Mostly False” for 26 percent of her statements (Investors Business Daily, June 30, 2016)."
PolitiFact is a fact-checking website focused on American politics. It is owned by the Poynter Institute for Media Studies. PolitiFact's website describes its mission to "give citizens the information they need to govern themselves in a democracy."
PolitiFact's "Truth-O-Meter" labels claims as "True, Mostly True, Half True, Mostly False, False" or "Pants on Fire."
"PolitiFact.com is a project operated by the Tampa Bay Times, in which reporters and editors from the Times and affiliated media outlets "fact-check statements by members of Congress, the White House, lobbyists and interest groups," according to its Wikipedia page.