It's probably not unreasonable to expect him to provide some help to someone standing next to him, and to some extent to the square as a whole. Few people have the ability to provide dynamic help to a whole square on a consistent basis, but to be considered really competent at a level, a dancer should be capable of providing this help on an occasional basis. A good dancer develops the ability to adapt to these new situations at a dance and at dance speed. Precise formations - Some people seem to spend all night dancing at a 45 degree angle with the walls. T-boned to the rest of the square and not know it.
Some dancers just seem to be dancing to the beat of a different caller.
These are some of the qualities I think constitute a good dancer. Okay, there may be others. It wasn't my purpose in writing this article to specifically exhaust the possibilities. My purpose was something else. Other things being equal, if dancer A makes fewer mistakes than dancer B, dancer A is a better dancer.