The greatest musical instrument ever made. A good guitarist can be easily identified by letting them tell you what music they listen to. They need not play for you. If a person listens to death metal, emo, screamo, and grunge they can be brushed off as poor players because they can only play a few power chords. If a guitarist listens to music such as Jimi Hendix, Led Zeppelin, Stevie Ray Vaughan, Pink Floyd, and other old rock bands they are most likely good guitarists or are at least on the right track in learning to play the instrument. Most teenage boys own a guitar though stopped playing after picking it up and finding out it takes a hell of a lot of hard work to make any progress with it. And I don't mean to sound sexist or anything, but females CAN NOT play.
Alex: Look at me! I can strum along to my favorite Fall Out Boy song!
Me: Dude put the guitar down and go write a poem about how no one understands.