I was a bit surprised to see an entire article devoted to this, as it's a very common in the theatrical world. Because of the short turn around time, directors are constantly having to work with new people. As well as calling people they know on the resumes, they will often ask the people collecting headshots and herding cattle outside the audition room if anything notable occurred. It can make or break an actors chances.

This is easy to apply to business. If you have a secretary greeting interview candidates, just get a quick opinion. Nobody wants to work with an asshole, and everyone remembers them.