Wet sanding the painted surface is the most aggressive vehicle scratch solution and can only be performed a limited number of times in the vehicles lifetime before a repaint is needed. Wet sanding should only be done by a professional. It removes defects in the painted surface several layers deep.
When done correctly wet sanding the paint will offer the best results in heavy paint damage, orange peel and paint blemishes and stains. It can be used to remove certain contaminants that may get on the paint as well. Often times it is used to bring an extremely weathered and faded paint back to life.