"I feel like I'm perhaps unfair on this or that because I learned something less flattering about it. "

I see now why my comment was down-voted. I should have put more emphasis in that sentence on the word because. That a unfair impression uninformed by fact is something one can't identify is not what I meant to say. What I'm cautioning is the idea of being very easily able to diagnose the reason behind the unfair impression, based on:

"well I was recently thinking about this and came to x conclusion about it, this must have spilled over"

why couldn't it be:

"well I was recently thinking about this and I came to x conclusion, and I've noticed I already had a unfair emotional response in place from before, maybe I should re-examine my previous conclusion in this light"

or even:

"well I was recently thinking about this and I came to x conclusion, I'm bound to see the world disproportionately in terms of this categorization, the unfair emotional response may well be an artefact to my dislike based on other categorizations"

Whack-A-Mole emotional counter conditioning seems likely to somewhat reduce bias, but I think its less effective and much more just a redistribution of unfair bias than first meets the eye.