I just took a CBJ class a month ago. What I took away most from it was what to look for as far foreign items not allowed in the box, ie. illegal garnish, shards of foil, hair, etc. Also, how to score boxes without the six identifiable pieces and such.
One interesting bit was that one box purposely had only five pieces of chicken breast in the box. We were told to score normally; however, once the 6th judge was left without a piece we would retroactively re-score the appearance (just in case the 6th piece was hidden or something). When a judge picked up a piece of chicken, it broke in half. The judge is not allowed to pick up the half that fell back into the box, so magically there was a 6th piece for the 6th judge after all. The table captain helping us got a kick out of that. Needless to say, that judge who picked up the piece that broke in half scored the box a 5 in tenderness.