The question comes up: how to judge a performance. Apparently there is some need to engage in this woefully irrelevant (!) activity. There is only one criterion for a good performance: Did they mean it, or not? Unfortunately, this quality is often among those edited out in the recording process: even, it seems, in the audition process, where everyone is expected to sound as much as possible like everyone else. Heaven forfend anyone should have a personal stake in what they are singing or playing !
Some of the most moving performances I have ever heard received very poor reviews in the press.