Look up ConfirmaTION BIAS
It works on both sides of the aisle.
Fwiw, NEVER stop looking in the mirror for that one! Being a good observer is harder than it sounds and thats a major reason why.
In my life, whether in my hobbies or academics or work, everything depends upon a scientific method approach and absolute integrity about taking accurate data.
Living by that understanding, and good penmanship, made me more valuable and trustworthy, and even kept me employed through many layoffs.
I think confirmation bias is a major inner programming flaw humans have. It makes us easy targets for all sorts of predators and con artists, even for our selves, and a good observer/data taker MUST self-test for it and overcome the tendency constantly.
Critical thinking is a learned skill. So easily fooled we humans are.