Seems obvious, but must be stated given the fact that rolling out the right beats is a critical fun factor at the reception and is what drives your guests to the dance floor.  You do not want to observe an empty dance floor, if, for example, the Chicken Dance were to be played.  It is highly recommended you talk to your DJ about your do-not-play list.  When consulting with your DJ, discuss your favorite genres, know your guests and discuss whether or not they will be permitted to make requests.