They can also assess overall situations pretty well. A friend of mine struck up a conversation with a security guard at the Austin City Limits music festival. He said he liked working that event because the people were genuinely there for the music. They were well-behaved and into the performances.
In contrast he said that another Texas music festival was a nightmare. Not just a bad dream, but a scene from a Stephen King story. Attendees at that event were not there for the music. They were there to be seen, to brag that they were there, to party, and possibly to feed on the blood of normal people.
May your concerts be ones that security likes to work. - Cris