I live in South Texas along the Gulf of Mexico and high humidity goes with the territory. I have not had an issue of scissors rusting. We do run our AC which keeps the humidity down in the house.

I live in Arizona and it is very dry here.

I don't know why anyone would not have AC during the summer in high humidity. A small window unit cost little of nothing and will keep one room cool at least. No need for duct work for those.

Onebyone, when we lived in Annapolis, MD our little Cape Cod style house had 3 window units. 1 took care of downstairs and we had 1 in our bedroom (hubby kept our door closed, he liked it really cold) and the girls had the other in their room. Our heating was baseboard and a small gas fireplace.

I use a product called "Naval Oil" made for rust removal. It is gentle on the blades and wipes right off.