This doesn't make much sense, but I can see when someone is really not a passenger, but cannot see it completely when they are. Sometimes I'll sort of have a feeling that it's the case, and then someone will mention that it is, but just curious about how you can conclude if someone really is one. What are elements you see that make really know??
Sort of an odd question, and I don't know if it's just because I am tired here, but please answer if you can. I am going now to take a nap before I study for my two last exams.