I hate to repeat this, because everyone's read it way more times than they want to, but...
Over half of my boxes are in a self-storage locker, several miles from here. When it comes to usage, they might as well be in Siberia! I visit them less than I used to visit my great uncle when he was in a nursing home. Fortunately, there isn't much dust floating around inside the storage roomette (not much air,either), so the boxes stay pretty clean. The belts and speakers get dry rot, but the boxes themselves stay clean.
As for the boxes privileged enough to reside at my house, one of them that I hate the most and use the least (if ever) is the big, black, empty Crown SZ-5100. Right now it's underneath my Oreanda RM-203 S (Ukrainian), where it will likely stay for years. It makes a very nice support/display stand! And, yes, the parts of it not covered by the Oreanda do get full of dust... which I don't remove. Why bother?