Diapers are not sterile when made but they tend to be pretty clean. Once exposed to a normal household atmosphere they will gradually pick up odours, moisture and dust, and possibly dust mites too. If your aim is to have some permanently on display, I would suggest rotating the stock so that no diaper that you want to use is left out longer than needed. Or reserve some as display-only that are never going to be worn. I unpack and decompress mine before use, but I put them in lidded crates to keep them clean during that time. My stock of older / unavailable products is all in lidded crates or original sealed packs as well, as I do intend to use most of them and want them pristine.