What I’m interested in here is that if you call someone a liar, you’ve got to  show them lying. It endangers PolitiFact’s hard-earned and important position as  referee in the mudslinging contest–a “truth vigilante,” as it were–for it to call someone a  liar on the basis of something that may or may not be false. Reid’s charges are  unsubstantiated, not backed up and at best hearsay. But his basic charge–that  someone told him Romney did not pay taxes–may well be true even if Romney did  pay. PolitiFact ruled “Pants on Fire” on the basis that Reid did not prove his  charge, meaning that it is now possible to get called a liar by PolitiFact for  saying something true. — More.