One thing that is certain is that the pool of people who opine they can be unbiased in areas where they have favorites is not the same as the set of people who can actually do it.
Equally clear is that a lot of people aren't even trying. An honest effort to be as unbiased as you can goes a long way.
Absolutely. I don't think anybody can fully succeed at that. But there's a world of difference for me between people who try and people who don't bother.