"Excuse me for saying this," says Stanley, "but that's real…

"Excuse me for saying this," says Stanley, "but that's really terrible."
"I suppose you can do better!" says the guide.
After Stanley plays, he says "Not bad! If you practice more it will be even better!"
Thus, the guide appears to give Stanley a boost by letting him outplay him on the piano, but he immediately turns it into a guilt for on not practicing enough.