One of the beauties of going out a lot is that you improve your people skills pretty quickly. Eventually you become so good at it that you are able to tell certain groups of people apart by merely seeing them.
The truth is that certain kinds of people like to go to certain Moscow night clubs. I am sure you know this: this club is famous for having these types but they would never go to this other club…and so on. Certain characters just repeat themselves over and over again.