I am bad at remembering faces. So when I notice an acquaintance in public, I would usually doubt myself if they really are the person I was thinking of or if they just had some similar facial features. So when I do see them, I would usually look at them but then just go on with what I was doing, or just pretend that I saw nothing. In college we had this monthly meeting for an organization I belonged to, then all throughout the session one of the seniors kept staring at me. It was weird, yes. Then at the end, he spoke and said something about seeing someone familiar among us. He said that he saw that "person" in a bus, but never greeted him or approached him. "So they are from here, after all," he said. Then he told us that the next time we see him, we should at least give him a nod, or a greeting. I do remember seeing him in the bus, but just like I said, if I am not sure about the person's identity I would never approach to say hi. I rarely get to see him and actually I am not sure if I remember his face now.