My buddy's dad was an old shade tree and liked to do things by "feel" and by sound. When we built the engine for his S10 we tuned it with a wideband and knock sensor, verifying our results at the track as we went.
A few weeks later, we go to take the truck for a spin and it's pinging like crazy. My buddy asks his dad what the hell he did to the truck and he said he "fixed it" because it wasn't running right; that we had the timing all wrong, so he timed it by ear. We put a light on it and it had like 35 degrees of base timing
We set the fuel trims using the wide band (had a Holley HP650 on it IIRC), again, this was verified at the track. Well, a while later, it was bogging like crazy and smelled rich and sure enough, his dad had changed the jets and "fixed" the carb because it "wasn't right". Had of course screwed up the timing again too.
We thought we'd solve the problem by putting on fuel injection (Holley TBI kit). Got that dialled, thing ran amazing. About a month later, we come by, the fuel injection was sitting on a pile of trash in the garage, he ripped it off because it "wasn't right" but he didn't know how to "fix it", so he slapped on an old Quadrajet and we simply gave up at that point.
People are not inherently sensory savants. Just because something is different doesn't mean it's "bad" or "wrong". Just because you are accustomed to the way something feels or sounds like doesn't inherently make a change from that a harbinger of catastrophic failure. What I'm seeing in this thread are examples of ridiculous hyperbole "oh, the brake squealers are all in your head"; something on the far end of the obvious spectrum, to justify the validation of things in the realm of sensory noise as being significant.
It's like somebody being questioned on their claim that they can "feel" the radiation from bananas and somebody sarcastically quips that having Tea at the elephant foot is totally fine because it's "all in your head". Intentionally binning the nuance because somebody clearly hit a nerve on a subject you are overly sensitive on.
Yes, it is quite possible to hear when things are "off" with a piece of equipment. Simultaneously, that does not mean that what you perceive as a slight change in valvetrain noise is good, bad or even there. That's why we have testing equipment that can measure the sound profiles and allow us to visualize what we believe we are hearing. No different than bumping the base timing and discovering I lost 2mph in the quarter, even though the engine "sounded better".