Actually yes, you can create bad out of thin air.
We've clearly defined that there are objectively good and objectively bad things, so no.
What you are talking about is subjectively interpreting certain events. It's conflating terms. You're not creating bad out of thin air, you're creating an interpretation, subjective, of something as bad. The objectively bad things were there always, you simply overlooked them, consciously or subconsciously.
Perception evolves and shapes how we apprehend reality. It works for stories too, you will not apprehend a story the same way if you trust the author or if you don't.
Yes, perception shapes how we apprehend a story, that's true, but when judging how well written something is we apply objective criteria and standards, and not our subjective ones.
If a writer makes a writing decision that is say objectively good and makes sense, you do not have to subjectively like it, and vice-versa. Your interpretation of that decision is well your interpretation and how you perceive it. Just because it is objectively good or objectively bad it doesn't make it subjectively good or bad. Maybe you liked an ending of an arc that was objectively bad, maybe you did not like an objectively good one, etc etc.
You can exaggerate flaws. You can exaggerate strengths. You can overlook either. You can interpret ambiguous evidence negatively or positively. Even non ambiguous one, subjectively tho.
But if you're arguing about whether something is well-written, you ultimately have to move beyond 'my perception that I chose' and justify why your interpretation better explains the actual text.
The good doesn't disappear indeed, but just like the bad, you can also shape things to see the good and even more good than what people usually see. This is how I function for ex with One Piece. I purposely shaped my perception toward the good side, I believe it to be a lot healthier than just seeking the bad. I see the bad, but only what is necessary to see, the rest is just an invention. You could say the same for me, but the difference is that my perception is positive and therefore create a positive chain reaction, rather than a negative one.
Well it is the same for you, and your interpretation is neither more accurate or truer or better. Your personal interpretation and approach is all yours buddy, but you cannot impose it on other people.
You're going at it backwards. You've already made up your mind and reached a conclusion, and are now filtering evidence based on that conclusion rather than shaping the conclusion based on the evidence.