How can one judge what is good or bad about a musical performance? Of course there is the basic answer of playing or singing the correct pitch on the correct beat. But then it is more of a test of accuracy. What dictates a good performance?
Some say it's emotional connection, others say its about raw talent and hearing that in the performance. Today, school choirs compete against one another. Of course they will be judged on their accuracy, but after that, any judgement given becomes subjective, based mostly on th judge's perference.