The bias I am referring to is not favoring one candidate over another in the wording of the questions, but rather to disqualify voters who may not vote the same way as you. An example might be "what did candidate XYZ say 3 years ago on this random radio talk show", and only die-hard supporters would be able to answer it correctly. (There are likely much better examples of what I am trying to convey here, but my caffeine level is dangerously low)