When I was some young age, probably about 10, I started riding the bus to downtown Houston to watch the street life.
I learned about the winos, the legless men on their push boards, (the precursor to the skateboard), I would watch as things started unfolding for me and the patterns developed of all the under life that lives in the downtown of a major city.
I knew where the whore houses were, behind the nondescript door of the cheap hotels and learned how the elevator operators worked as front men, I watched all the wheeling and dealing of taxi drivers and businessmen and street hustlers.
As you sit on a bench for hours, invisible to the grown ups and watching, you see all kinds of things and connections, and interactions, and people pretending spontaneous contact with a stranger passing through the zone, and the little scams and all kinds of things that are not obvious at first.
Yeah, gramps would just talk about how he was a kid in NYC just walking around looking at stuff - buy a frank and a Nedicks orange soda ... take the subway home ... on weekends he’d take a subway to Canarsie, maybe to the beach there. Thing was, he was only 8 or 10 ....
You could have been a private eye with that training.
Or at least written stories like Dashiell Hammett.