A compilation of several questions from several readers boils down to:
Don't professors remember what it was like to be a student?
That is: Don't professors remember what it was like to learn something for the first time? Don't professors remember what it was like to take a boring class (so why would anyone teach a boring class)? Don't professors remember that exams are stressful (so why would anyone give an exam, especially a stressful exam)? And so on..
Well, I think it's fair to say that we sort of remember and we sort of don't. Is it so different from how parents don't really remember what it was like to be a kid, or even if we do, we have changed our ideas about how adults should think and act?
In a way, it is different because parents are all-powerful and infallible beings, but professors who teach may still be learning how to do so, may be teaching a course for the first time (even if they are "old"), or may be trying out some new material in an old course. We are supposed to try to find inspiring and thoughtful ways to do so, but this isn't easy. It isn't that we've forgotten that we shouldn't be boring and articulate, it's just that teaching requires considerable skills, and some of us possess these skills in less abundance than our students would like, despite good intentions.
But consider this: In some of my classes, students give presentations. I am always very entertained by the fact that the vast majority of students create presentations of the sort that they would definitely hate if they were listening to the presentation rather than giving it. Even if I discuss in advance how to give a good presentation and even if these students know exactly what they like and dislike about presentations to which they have been subjected by professors, most of them will have dense, text-filled slides that they will read, word-for-word to the rest of the class. Most of them will have no clue how to explain a topic that they have researched intensely but about which their audience knows little or nothing. I watch the presenting students glance with annoyance at their fellow students who are sending text messages during their presentations. It is fascinating. We have much to discuss after the first round of presentations in each class, and presentations do start to improve after that (although some never let go of the text-filled, narrated slide mode of presentations).
I see the same thing when graduate students and postdocs give informal presentations in my department. For example, an individual who had mocked a professor who gave a text-slide filled talk just weeks before did the exact same thing in his own talk. Why? Why don't we all learn from what we observe in others? I don't think the main cause is related to age and distance from one's student days. Based on these examples, it seems to be human nature.
Even so, I think there might be an element of age to some of the situations that motivated readers to wonder whether professors remember anything about their academic youth other than their GRE scores. For example, when we teach a class year after year after year, we know exactly what questions students will ask, we know what concepts will be most confusing, and we can work to improve our explanations, examples, and presentations accordingly. Despite this, I have, however, noticed a tendency in myself to forget what exactly students know and don't know about some topics. That is, when you've explained something a billion times, you may start to forget that there are aspects of it that may be completely unfamiliar to students encountering the topic for the first time. Or, if you've spent many many years teaching a particular class, you might get bored with certain topics and decide instead to liven things up by talking about a new (but more complex) topic, skimming over or even skipping some elementary concepts. Each time I (re)teach a course, I have to think very carefully about the basis from which I should explain each important concept, and each time I have to (re)work out the logic of my explanations. Some things about teaching get easier with time, and some things get more difficult.
Not long ago, I spent 3 years working my way through the beginning, intermediate, and advanced undergraduate courses for a particular language that is useful for my research and my international collaborations. If you had asked me before I took these classes whether I remembered what it was like to take an exam, I would have said "Of course, I've taken a gazillion exams." I was very surprised to find, however, that I didn't really remember, at least not in a visceral way. But even though I was a 40-something professor taking a non-degree course pass/fail, I got very stressed out about the exams in those classes (in part because the exams were impossible, but that's another issue). Nevertheless, I know that the exams, and the act of studying for them, helped me learn important things, even though I hated taking these exams with every molecule of my being.
That's why my answer to the basic question is: yes and no. Yes, we remember, but maybe not in a visceral way, and even if we do remember, it doesn't necessarily influence whether we are good teachers or not.
Something that students could do to help us ancient, disconnected professors (and, therefore, help you, our students) is to ask substantive questions that help us figure out what you know and don't know and to give constructive advice (on evaluations, for example) about teaching style. And if that doesn't work, you could scream "You just don't understand!" and stomp out of the room, slamming the door. Maybe that will jog our memories of what it was like to be young.