Thank you so much.
I dont know that I have a trick to keeping the polaroids clean. I do clean the glass and polaroid before every polaroid I scan. That helps a lot.
Also I do a decent amount of dust removal in LightRoom to clean up the dust that does get left behind. Other than that its just a matter of keeping the polaroids properly stored and not messing with them too much. I use to keep them out more but found that shuffling through them a lot would scratch them a lot. So I store them away now-a-days.