Offizieller Kommentar
I have not seen this with my 1000s and the XZ being so new, can't say I have see it with that unit either. We did have one out last week in AZ and it was played with a lot and exposed out of the case for 5 days and no visible change to the displays. I would expect it would follow the DDJ-1000 and stay clean on the inside. Just got it, maybe return for a new unit??