Every time I see one of these post I think about the arcades at the Jersey Shore years ago. Those machines were right next to the ocean in salt air all summer then stored in the same unheated damp arcade all winter and most survived.

With that said I have never bought a machine out of NJ that was in super nice shape likely because most came from the Jersey Shore at some point.

Not climate controlled is basically hit & miss. In my eyes nice machines should stay in climate controlled environment if possible but "players quality" machines I really don't think it will matter all that much.

Actually a bale or two of hay will do the trick also as far as moisture goes. Something about dry hay just sucks moisture out of the air very well.