In "Why Don't You Dance" by Raymond Carver, what has the girl discovered about life as a result of her encounter with the drunk man?

I think it's like what the garage sale represents; both the couple and the man are both unwanted, lost, useless and lifeless. Adding on to what gbeatty said, it really does give us a sense of emptiness in both characters, and how commonplace their life is.

It doesn't matter if you're young, or if you're old, bitterness is universal, and the young couple blends right with the old, pathetic "middle-aged man."

I think the ending is the most, I don't know, in-your-face part of the whole story. It's just, you get such a pleasant feel from the man, and you really can see the warmth and the semi-intimate atmosphere of it all, yet they just treat it like a weird story to see.