Sometimes prospective clients ask me if I’m able to send them a demo CD. I have never produced them because I feel they do not accurately reflect the quality of your DJ. Anyone can record a load of songs onto a CD but it does not indicate how they would react to a dancefloor emptying. A good DJ constantly watches the audience and their reactions to each song he plays, this dictates what to play next, this is impossible to replicate on a CD. And it’s not just a matter of watching the people on the dancefloor, but also watching reactions to each song of those that aren’t dancing.
Additionally, the music that you put onto the CD can turn prospective clients off; if for example the DJ put a lot of newer stuff on and the prospective client was looking for slightly older music, or vice-versa, or if you put lots of different styles of music onto a CD it may well not “flow” very well together.
Lastly, it has been known for DJs to send demo CDs that have been recorded by someone else! So in my humble opinion, demo CDs are of little value when all things considered.