By this point everyone on the planet has played Guitar Hero. And all of these people can be placed in a category.
The Beginner: This is the person that has just picked up the axe for the first time. He has no sense of rhythm and couldn't even spell hammer on. This guy saw Guitar Hero at Best Buy while he was buying Super Bad and decided to try it because he had heard so much about it.
The Crafty Veteran: "Dude I just FC'd Free Bird."
The Tricky Dick Nixon: This is the person that brags non-stop about how good he is at Guitar Hero, and when you ask to play against him, he will usually come up with an excuse like "I'm too drunk" or "I have MRSA". Eventually he will be cornered and force to play, and everyone will laugh when he can't even beat Slow Ride on medium.
Mediocre Hero: This guy almost beat hard. He only needs to 5-star five more songs on medium. And he already beat 13 songs on expert. He is, and always will be, just OK.
"Real guitar is better" Guy: This guy is absolutely terrible at the game, but can play a few Jack Johnson songs on the acoustic guitar. He tries and ties, but never gets better, so instead tells everyone that is playing that real guitar is better. Well screw you. It's easier to play Guitar Hero when you're drunk.