I once went to Guitar Center where some guy was sitting on an amp playing a Les Paul and hammering the neck with the right hand like a man possessed. When he stopped to breathe I said "Cool. Can you show me a b flat major 7th?"

He glared at me and gave me a 2 word obscenity that rhymed with "truck zoo".

Moral of the story: Being able to play a lot of notes really fast does not make you good.