An SOS pad can get most of the light scratches and dirt out, but it will dull down your shine on the plastic. Get some polish or something to get the shine back. As far as deep gouging scratches go, you can't really get those out to easily, you can make them less noticeable by wet sanding them with about 1,000 grit paper and then move up to about 1500 grit. This will also take the shine off the plastic though.
