With ladies shoes it becomes obvious. Stand your shoes on a flat surface. If they lean outwards you are using the outside edge of your shoes. It should be the inside edge. If you are looking for balance problems you could start right there.
If your dancing has been to the outside you have turned a good pair of shoes into something that is now useless.
Guys should be able to see from the wear on the sole of there shoes as to which part they are using.