Hi,
If you think of the tow-ball as a mini-Earth, then the AL-KO frictional pads press on the equator and extend no more than 30 degrees either side - or rather that's what it looks like to me.
If you've got scratches close to the top - then those are probably from grit or similar - caught between the top of the tow-ball and the very top of the caravan tow-coupling. And so those scratches shouldn't matter too much.
Years ago when we had a car with a flange plate AL-KO tow-ball, we also noticed this was prone to scratching around the top - changing to a detachable / swan-neck style ball has significantly reduced this - so I can only assume thata different steel is used...
Robert