When you go up to perform, the poeple that watch you perform, they will have a thought bubble either with the musical note with a circle in it with a thumbs up or down. If you get a thumb up with everyone they like it, the thumbs down indicates they are not impressed. At the end of you performace they will vote and if you see the image of the reward bouble come up either during your performence or after it means that sim voted for your sim to recieve the reward. The more sims that display the star trophy in their thought bouble the higher the chances. Another thing sims that have no celeberity ranking will count vary low when voting, but celeberity ranking of 1 star gives 10 points 2 gives 20 points 3 gives 30 points 4 gives 40 points and 5 gives 50 points. So you will need to beatout the other celeberities in your game to get the reward.
Edit: The musical note is just one example, that relates to music.
The rewards are the Best dressed in the tightest cloth
The 110% best actor reward
The friendliest sim in del so valley
musical genies
There could be more but they are not active in my game.
