One of the things that seems mentioned the least in the training of PhD students and post-docs is what I would call "your scientific gut feeling": this intangible feeling for what topics will be important, which questions will lead to important answers and which unexpected results can lead to important discoveries. I actually wouldn't know how you would train this in somebody, but I think it can be very important in somebody's career and for science in general.
I seem to have the reverse scientific gut feeling: the first time I heard about LTP in the hippocampus when I was in college I had some type of unexplainable aversion against the topic. Later, I had to admit that when this was the basis of learning and memory in the brain, I guess I had to start liking it a little bit.
Similarly, the first time I heard about a project I got involved with in my post-doc lab, I was extremely skeptical about the mechanism that we were studying. So much, that I started to look up evidence to disprove my PI's hypothesis. In the end, I had to admit that perhaps they were right, and the paper about this ended up in a pretty good journal, which I honestly had never expected the first day I heard about it.
So now, when I sit in a meeting and somebody talks about a method or results that make me feel annoyed, skeptical or even almost angry, I stop myself from asking skeptical questions, but I realize that this might be a very important topic and that this feeling may actually indicate that it is important.
How is your scientific gut feeling? Or how do you identify important topics or results?