I have indeed sanded out slight imperfections, like dust, with very fine paper, then gloss-coated and got a good finish. The key is very fine paper, at least 1000 grit. In order to eliminate much orange peel with such fine paper, you need to have patience, because it takes quite awhile. If the paper you are using makes the finish look dull or matt without visible scratches, you are okay. But glosscoat will not cover any visible scratches or sanding marks....