Paint correction is physical leveling then refinement process to remove scratches and other paint defects by compound and  polishing to the clear coat of the paintwork. All of my paint corrections  include a RESET exterior cleaning to fully debride, clean and decontaminate the surface of the vehicle to provide the best surface condition prior to any correction work. All vehicles and client expectations differ, and I always encourage a full inspection of the vehicle condition prior to scheduling the work. From there I will recommend the best option for the client's vehicle and your expectations of the service and process. Deeper scratch removal will require scratch and scuff repair, which may require wet sanding and  touch up paint pen to achieve optimal results.