From the the years of doing Zumba, here is my wish list for a good instructor. They:
1) Focus attention on the participants. It's never about themselves performing on stage.
2) Listen to and take onboard feedback from the class.
3) Plan their classes, never "winging it".
4) Get to know their participants.
5) Never show weakness or complain on the stage.
6) Never speak negatively about other instructors or participants.
7) Change their playlist every month or second month.
8) Keep breaks as minimal as possible, most times don't take breaks at all.
9) Show up early for their classes. Start and finish on time.
10) Do moves that flow well with the music.
11) Do quick cues clearly and consistently from the 6 or 7th beat.
12) Demonstrate the moves with energy and enthusiasm.
13) Take control of the class without being aggressive.
14) They're shining ambassadors for the fitness programme, Zumba.
15) Display confidence, smile and create camaraderie in their classes.