Ailes has a blunt rejoinder to those who say he runs a biased outfit: “Every other network has given all their shows to liberals. We are the balance.”
There is a difference between being the balance and being yourself balanced. If you miss that little distinction, "fair" goes along for the ride. If your notion of "fair" is giving two sides equal opportunity to manipulate and distort information, then Fox arguably makes the mainstream media more "fair."
Most news media other than Fox make a reasonable attempt to be themselves balanced, not ballast. Fox makes it hard for the other cable news networks, though. It degrades the whole medium.
You can throw shit in equal measure on two ends of a scale and get "balance." That's the Fox version of fairness.