Most people think they are fair-minded and unbiased--including me. (Well, that is a complicated matter: I am now aware, in retrospect, that when I was a anti-Soviet/pro-West during the Cold War, I turned a blind eye to various U.S. dirty tricks.) I think this is necessarily true, for, to paraphrase Plato, we do what we think is good--by definition, perhaps--and to admit bias is to know that one is deviating from the good.
Whenever I watch a sporting event (NHL, MLB, etc.), it's always the other team that has done something outrageous, and my team is always the victim. Example: Brett Hull violating Hasek's crease and costing the Sabres the Stanley Cup. But, of course, it is improbable that the teams I happen to cheer for are morally superior, year after year. Clearly, I am interpreting events according to my favoritism. This is quite troubling, because I can't see how it happens. I honestly can't recall when my team has been at fault. (But, armed with this insight, I will be paying closer attention the next time I see a game.)
Other examples: in any anecdote, the storyteller is always in the right. Here we can tentatively conclude either that people are silent about incidents for which they are to blame, or that they genuinely fool themselves into believing themselves innocent.
But I am interested in the sporting bias, because it seems to be straightforward, unvarnished, and unmediated.