I clean the ball until it's as close to mint as I can get it without a total re-surfacing. Even polish dried into scratches I remove. If I don't like the way it looks, If I would not want to get that ball, I don't send it.
If the ball has the beginnings of a track, so that you can cee the whole track, even if only barely, I will try to take many of those scratches out via a minor re-surfacing, maybe 400 grit sandpaper and take it to 600 and polish, if it came polsihed. I would not do a total, which for me is 180 or 220 grit to remove as many scratches as possible, without making the ball smaller.
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"Just because you can do something does not mean you should do it."