When someone speaks to you, you should ask yourself:
As a leader, we cannot afford to take things are face value: there is always another layer to observe, or another angle to observe it from.
When I study martial arts, I must think very clearly about where my feet are, where my hands are, where is my sparring partner, and what kind of signals, or tells, they are involuntarily making to indicate what they are going to do next. I must clear my mind, and live in the moment with heightened awareness.
In a business setting, such moments also exist when we must process a lot of real time information about the people around us, which if interpreted correctly, can help us predict their next actions.
People give of clues about their intent constantly, you just need to be mindful of them. I once read in a text about body language that most of our communications are non-verbal, and I firmly agree with that. Some examples include:
To be a leader is to be a student of people, and people give off many clues that their intent is often in direct conflict with their words.
We all judge each other, whether we admit it or not. We judge on appearance, competence, trustworthiness, confidence, and many more criteria. Judging others is a survival mechanism, it's a fundamental part of being human. You too are also being judged, even if they say nothing.
In order to make sure your judgements are accurate, work on your observation skills.