A pirouette in classical ballet will often not change positions during the turn, and if it does, its a change that looks purposefully done. (like from a front attitude, into passe, into a back attitude for example). But what you want to avoid is having different positions of your body throughout the turn and each time you spot.
This is one of the best tips for cleaner pirouettes. For example, once you establish your retiré leg and begin (the best possible one you know you have, of course), it does not move. It does not figgit around, lowering the hip or changing the position of the foot on your leg. Once you get into first position with your arms (unless of course the pirouettes calls for the arms to go into another positions), try to show the exact same position at every point in your pirouette, so if someone took a picture, the only thing that would change in each picture is your head spotting around.
Try to think that nothing is moving out of place, with the only movement being your head as it spots. With a cleaner pirouette, the audience will be able to better enjoy and see each individual turn. This is often how dancers who do only three “look like they did 6!”
