As a master ceramic arts judge, I am asked from time to time if someone who is entering a piece in competition is using bought bisque, should they still be penalized for imperfections in cleaning and or casting. The answer is an absolute "YES".
There was a time not to long ago where bisque was entered into competition under a separate category, or it was judged in a craft section along with plastercraft. Today we know that this is not a feasible or appropriate resolution.
Today if you are serious about competition and still want to use a bisque kanvas to start on you should invest in a good quality Dremel or Dremel style hand held grinder/cutter. It takes a lot of practice using a Dremel on bisque, and bisque is totally non-forgiving in your clean up work.
Quality of workmanship is the first component in judging. Also always remember that there are some things you can do in the leather state of greenware (i.e. clay lifting) that you can not do in any other stage or with any kind of tool. Always make sure you have all the right tools before you start any project.
You should do every project like you intend to enter it and win the TOP AWARD!