Can human bias affect scientific observations? NO, not in genuine science!

To offset such human mind inadequacies like cognitive biases, fallacies, cognitive distortions, cultural, traditional and religious conditioning of minds, we have something called the scientific method.

Image source: What's New at Science Notes

Then it goes for peer-reviewing, post publication reviewing, falsification, and result reproducing tests.

Do you think you can escape all this?

NO!

And critical thinking the intellectually disciplined process of actively and skillfully conceptualizing, applying, analyzing, synthesizing, and/or evaluating information gathered from, or generated by, observation, experience, reflection, reasoning, or communication, as a guide to action.

Just because you are emotionally involved with something, believe that something is true, it doesn't become truth and a fact of science.

We all know this and don’t allow our biases and emotions to interfere with our work.

There are a few thousand scientists; it wouldn’t be reasonable to believe that they: 1) could coordinate a falsehood, 2) agree to reiterate the falsehood, 3) fabricate the supporting evidence to sell the falsehood. Doubly so since their professional career is predicated on accuracy and precision, and being in the rare position where you discover something surprising and support it (as debunking a lie would be) is as close as a scientist will get to fame and fortune. So, they can't take a chance and deceive the world. It would become the end of the world to them. (1)

Agreed there are grey areas in science - recently several of the scientific bodies have accepted this and decided to take corrective steps. That is the beauty of science. You accept your mistakes, agree to get corrected, and actually take steps to right the wrongs (1).

Peer-reviewing, testing others' experiments by repeating them, retractions of papers if the results are found not to be true - one cannot escape punishment and shame if fraud is involved. Nobody can break-free from these controls and hawk eyes and constant glare of the experts in his or her field. Only people who have undergone all this fire-walk to prove themselves know how difficult it is to stand as a genuine scientist - I have first hand experience in this field - where people try to rip you apart if you are not truthful and confident about your work. If something has passed all these filters, then you can be reasonably confident that it is true.
If you still doubt this procedure - you are not thinking in terms of science but in terms of art , religion or other subjects - where only opinion and belief count. The field of Science is trust-worthy because it has in-built corrective procedures. (1)

You cannot cheat the system forever. Your colleagues keep challenging you over and over again. They repeat/use your work as base to theirs. If it doesn’t work, you will be in trouble.

So, scientists usually try to be honest by controlling all human inadequacies. If they don’t, their careers will be in trouble. Therefore, most of the time, they don’t affect the observations.

That is why we trust the scientific method. You can’t find a more trust-worthy method in any other field.

Footnotes:

1. Standing Up For Science : Showing Reasons Why Science Should Be Tru...

(This is my own article)