Film editor Walter Murch nails a concept I have long been looking for a way to express: "referred pain", the idea that people's complaints are good at telling you when something is wrong, but bad at telling you what.
When you go to a doctor and tell him that you have a pain in your elbow, it is the quack who takes out his scalpel and starts to operate on the elbow. Then you wind up with not only the original pain but probably a pain in your wrist and your shoulder as well. Whereas an experienced doctor studies you, takes an x-ray, and determines that the cause of the pain is probably a pinched nerve up in your shoulder—you just happen to feel it in your elbow. The pain in the shoulder has been "referred" to the elbow. Audience reactions are like that. When you ask the direct question, "What was your least favorite scene?" and eighty percent of the people are in agreement about one scene they do not like, the impulse is to "fix" the scene or cut it out. But the chances are that that scene is fine. Instead, the problem may be that the audience simply didn't understand something that they needed to know for the scene to work.
So, instead of fixing the scene itself, you might clarify some exposition that happens five minutes earlier. Don't necessarily operate on the elbow: instead, discover if nerves are being pinched somewhere else. But the audience will never tell you that directly. They will simply tell you where the pain is, not the source of the pain.
This is a deep and pervading phenomenon. The idea is drawn from the medical field. Murch uses it in the context of moviemaking, and it would seem to apply to all creative fields. It even extends to political movements and mob action, where the core complaint may be fundamentally off, and yet nevertheless a group of people have rallied around it.
In Murch's example, the audience had no chance of identifying the source of the pain, since they had no access to the missing exposition. Even with the access, we wouldn't expect the audience to be able to do the editor's job.
There are however many examples where people do know the actual source of the pain but are unable to communicate it. In my experience the number of competent people far outweighs the number of communicators. For instance, people have an innate sense of when they are being cheated, but when pressed they may be unable to give you a cogent explanation as to why.
Similarly, a commuter may know his morning drive by heart but be unable to give useful directions to another person.
The first time I taught a class was a rude awakening. Concepts I thought I knew inside and out I found I was unable to convey. That machinery in the brain had been dark the whole time.