When manufacturers grind their bearings for car engines they pay attention to the direction of grinding because microscopic burs form on the trailing edge of the metal. Sanding also produces burs and polishing can’t remove them entirely.
So what direction should you sand the axel for which wheel? Dremels and drills in their forward setting will grind an axle suitable for the right side of your car (assume you are the driver). To grind your left wheel axles reverse your drill direction.
Another thread asked what wheel to lift on a 3 wheeler. This gives another reason to lift the left wheel since it needs to be special.
Terry