Live players are in creative communion with reality: processing feedback, learning, and adapting to circumstances. In Samo's definition, they're able to do new things outside of their expected domain. Dead players are repeating stereotyped behaviors, often cargo-culting what live players have pioneered.
One sure-fire way to tell that someone's alive is when they surprise you. I think this explains a lot of the appeal of artists. Even if their art isn't particularly compelling, at least they're making things that have never been made before.