To extrapolate from this, in a very dodgy way…
If you don’t communicate what you’re really feeling in a dance performance, the audience won’t feel what you’re really feeling. If you plaster a fake smile onto your face, your audience won’t feel the joy you’re trying to fake.
So I guess the challenge, then is to actually be emotionally invested in your performance. Or to at least be really good at faking a real emotion (or set of emotions). That means more than a fake smile. Elite dancers are very good at isolating parts of their bodies – different muscle groups, etc – and then engaging them for very specific responses. So good dancers are also really good at faking emotion. Thing is, though, most dancers in performances aren’t elite dancers, and they aren’t terribly good at faking emotions convincingly.
This really leads us to people like Stanislavski, I guess, who had his actors (who are people who make a living from convincing audiences they feel something) train as dancers and singers and so on. Good dancers, then, are good actors.
When I watch a dance performance, I want to see real things happening. I think this is why I like performances most when something goes wrong. I don’t like to see people hurt or humiliated, but I do like to see something unexpected happen. Best of all, I like seeing how people respond to that unexpected thing. Probably because that unexpected moment allows us to really see what that dancer is really like.