One of my main points in setting up this blog is to try to help instructors and students in those situations where a student has a question that truly stumps both learners and instructors. However, when you are in the moment of actually teaching, sometimes you just can't come up with a good reason why a particular word or phrase "works" better than another. Or you know that the wording that your student is using is wrong, but you just don't know how to explain what is wrong about it.
Last night (while drinking), I came up with a phrase that could be useful in these situations. "My native speaker spidey sense tells me that this is (correct/incorrect)." I know, it's not that useful a phrase for those instructors who are non-native speakers. Maybe these instructors could just say "my ESL instructor spidey sense" if they need to employ this blanket statement of "I know what's right/wrong, I just don't know why."