"They didn't act like people and they didn't act like actors. It's hard to explain. They acted more like they knew they were celebrities and all. I mean they were good, but they were too good"

This quote by J.D. Salinger is referring to a group of stars he had actually seen in a play. He is explaining how they acted in a different way than other actors he had seen before. He noticed that they acted as if they were currently celebs, as if they were already popular. He discovered their performance to be great, however too excellent, as if they were attempting to show off their skill. This quote suggests that the actors were not as genuine in their efficiency as they might have been, which they were more focused on looking like celebs than on delivering a genuine efficiency. It is possible that Salinger was dissatisfied in the stars' lack of authenticity, which he was expecting a more authentic efficiency.