If you are going in for an audition for, lets say, A Chorus Line, it is a good idea to go and see the show to know what parts you may be considered for, or more importantly, what parts you will be understudying.  Right now, in A Chorus Line national tour, all of the girls in the ensemble (or the "cut dancers" because after they get cut at the top of the show, they stay backstage and sing background until the finale) understudy or cover one or many of the principals.  It is this way for several shows nowadays because the ensembles are getting smaller and smaller due to budget constraints.  Therefore, the creative team (producer, director, choreographer, casting director, music director) is going to be looking at where you fit character-wise.  Long gone are the days when a dancer could just go in, be fierce with turns and kicks, and get a Broadway show.  You must be an actress and a singer and most importantly, know the show that you are going in to audition for so that you can walk into the room to sing your song after you've made the dance cut and knock their socks off!  Believe me, the casting directors want you to be what they are looking for, especially if you've made the dance cut, and they think you are a fantastic dancer.  It makes their job easier, so never think that they expect you to be bad because you are such a "dancer dancer".  The expectations are high nowadays, so go out and do your research and get your voice and acting lessons in just as much as your dance classes because these are as much if not more important in todays Broadway world!