I have had this "problem". I use screen protectors and it's a smudge, it just wipes off. I do also keep a cloth in-between the screens 90% of the time (by habit, done it since my DS Lite).
Dunno what the big deal is.. is it actually damaging the 3DS for some people?
Dunno what the big deal is.. is it actually damaging the 3DS for some people?