Is it a useful skill reading into the subtext of a conversation? Is it an ability to be cultivated or extinguished? There seems to be a certain arrogance to it....reading between the lines of what a person is saying, drawing inferences that in actuality may be completely invalid. Unless there is a general mistrust of the other person's ability to directly communicate, should it even be necessary. Perhaps in the inevitable void created by things left unsaid, one can't help but to try and attribute meaning, whether it exists or not.
I also wonder if it isn't a little passive aggressive to expect a person to understand the motivating force lying beneath a conversation and to read between the lines.