It's especially fun with strangers and you get better and better at it the more you do it.

A well targeted quip or joke at the right/wrong time and then glimpse at their reaction will tell you a lot about said stranger.

It can even act as a filter. Based on the way they react, you may quickly decide if it's worth investing more time and effort with the niceties and interaction.

(im not a sociopath, i promise)