That's quite a sensitive test, though. I'm trying to make my views unbiased. If I succeed, someone who still exhibits a greater amount of bias will either disagree with me, or I'll disagree with their reasoning.
Well, you might have different priors, leading to different posterior beliefs from the same data; or you might have different values, leading to different decisions or policy prescriptions from the same descriptive beliefs.
(One might expect that a person raised in a large close-knit extended working-class immigrant family might have different values regarding economics than a person raised in a small individualistic nuclear middle-class ethnic-majority family, for instance.)
The last point reminded me of speculation from the recent LessWrong article Conspiracy Theories as Agency Fictions:
Before thinking about these points and debating them I strongly recommend you read the full article.