Sykes put his finger right on the problem ("he" is PolitiFact writer Dave Umhoefer, "they" is PolitiFact):
Though evidently quite ready to admit a error if proved, Sykes makes a good case in noting that PolitiFact holds a different standard for its claims of truth compared to those whose statements it rates.So, in other words: he did NOT verify the Brennan Center numbers. Instead they relied on an overtly left wing source's "estimate." (Try to imagine the JS ever relying on a Koch Bros. financed group's uncorrobrorated estimates to label a liberal a "liar, liar."
They did NOT verify the Kloppenburg numbers.
They did not include possibly big outside spending by Big Labor.
And they decline to offer any other hard data to support their story... the sort of documentation they demand from others and which they use to declare that others are "liars, liars."
Ironic.(all caps emphasis in the original)
It's called hypocrisy, and it is expressed directly in PolitiFact's statement of standards:
Burden of proof -- People who make factual claims are accountable for their words and should be able to provide evidence to back them up. We will try to verify their statements, but we believe the burden of proof is on the person making the statement....except when the person making the statement is a PolitiFact writer.
Sykes' story is especially instructive as he quotes his correspondence with PolitiFact staffers, so please read the whole thing. My experience has been similar to his. PolitiFact staffers do not readily acknowledge problems with their process or results.