Just because people don't like a particular person doesn't mean they are
biased against them. Their dislike could be rooted strongly in the actions the person has committed.
By the way, its very difficult to prove bias against a single person as opposed to a group.
With a group, you can show bias easily by pointing out someones dislike for a member of the group who only shares superficial traits with the rest of the group (e.g. ethnicity/nationality/gender/etc.).
But for a person? Even if you're suspicious of every seemingly innocuous action of them, it can be justified by saying they have lost your trust due to actions in the past.
