What makes a good DJ?

We will add pointers - as part of ongoing series-of-pointers. A good DJ listens to the Event-Organizers / the Party-Makers - those who are putting the Event on / putting the Party together. As part of communicating with clients / organizers, a GOOD DJ, will assemble an appropriate music-play-list, well before the actual day / evening of the event. Many clients I have spoken with, when talking about DJ's they had previously hired, noticed that they (the other DJ's) were not prepared and / or that they did NOT play music that fit their crowd or situattion.