How Do You Distinguish?

Read a book, saw a play, in this case, about the traffic in young girls for the sex trade, by unscrupulous men. In the past have noticed the infrequent street walker but demographics change when it’s summer in the City: lots of tourists, and lots of folk away. The first couple that brought the question to mind was seen two days ago at this entrance/exit to the subway that now has been identified in my mind as possibly sketchy. He, not tall, very fit – trim to a remarkable degree- was leading her tall, thin, 20’s or 30’s?, with a cane and in passing perhaps somewhat disoriented. What caught my eye was the lack of compassion on his face. Then last night, boarding after me on the subway at another station. She was foreign, giddy not a great physical specimen, not noticeably well-dressed, perhaps 20’s. He was better dressed, great voice, and completely solicitous to her conversation and her chatter, because that’s what she was doing, chattering. She gave off the energy that she was enthralled with him; somewhat as if she was unable to believe her luck in being with such a divine creature. His eyes when we exchanged glances, were more receptive.  Where these just random dates? Need I question the coupling of the handsome male with the lesser female? I see it frequently in older couples, why the suspicion around younger ones? In both cases they were from different races and/or ethnic backgrounds.
Just a thought