I’m sanding taped joints and skim coats.  All purpose compound.  Picked up a radius 360 round sander with 220 grit.  Using that, I get lots of small scratches with brand new paper.  It sounds like that might be normal but i’m surprised because the 180-grit hand sponges that I’ve been using leave no scratches at all.  Another round pole sander with different 220-grid paper also doesn’t leave the same scratches.  Am I doing something wrong?  Something wrong with the sand paper?  Do some types just leave a smoother surface than others?