Certain content might be more or less blatant about it, and as seymour1 suggests, gathering that additional data and cleaning up the currently actionable data really only has upsides.
One avenue would be to put those who report the same things as biased in cohorts, to be shown or not shown similar content.
It's not like being exposed to content biased contrary to our view changes our view; it's just more readily detected as biased, and in certain ways may reinforce our view as we defend it.
In any case, the ratio of bias reports/views for content is likely to be inversely related to its value and general appeal.
One avenue would be to put those who report the same things as biased in cohorts, to be shown or not shown similar content.