Way back when, there was a song "The Universal Soldier". It's so far back that even recalling the first line -without resorting to some form of Internet Research (ie Googling) - is just about impossible for the average Person In The Library, let alone the Man in the Street.
But thanks to the wonders of modern technology, together with the brilliance of a human mind, "they" have come up with a composite graphic for The Face of any city, location, and - by extension - presumably mindset.
It may (or may not) be a simple progression then to produce a composite face for a library's most valued clients; and one for known library vandals, returns defaulters, computer regulation violators, and other categories of miscreants.
What we could actually do with such a graphic leads to so many possibilities, it makes one's ears bleed just from thinking about it. But that could be just me ...