Two rules for gamertag I have found to almost always be true: 1. The badassitude of a persons tag is inversely proportional to their skill ie someone named "MLG_Pro Legit" will almost certainly be terrible 2. Anyone with any version of snipe or sniper in their tag will almost never be seen using a sniper weapon. --- Time magazine's Man of the Year in 2006! Really. Google it if you don't believe me.
I sorta agree with TC. Games can rank you on all sorts of stats, if I remember right even MGS back in the day gave you a title. I think it'd be quite a nice feature if you had some sort of title or trophy that defined your general play style.