This thread kind of ties in with that discussion on emotions vs feelings. I can read emotional cues from others very easily - that is, when someone else is feeling an emotion I am very astute at picking up their non-verbal cues or signals. I notice things like the toe-tapping, increased rate of breathing, and subtle changes in facial muscle tension. I am pretty good at interpreting what kind of emotion is being experienced, and I can usually pinpoint when this change occurs in the context of the situation.
However, without checking in and hearing first hand from the other person I am as clueless as anyone else about what *feeling* they are experiencing and the exact cause of it. I can hazard a guess from the context and my own feelings and experiences, but that is all it will ever be - a guess. What I have learned from experience is that although I am sometimes right about the whats and whys of other people's feelings, I am more often wrong. Other people have a whole realm of experiences, triggers and complexities that are different to mine, and believing I *know* what they are thinking and feeling without asking them first is a bad idea.