Yeah - some parts of the country that's true of anything you don't wear for three days running - and a whole lot of the country has fallen into that camp this year. I just found some mold on the strap of my computer bag. You'll have that when it's humid enough that the carpet squishes when you walk on it.

I guess it depends on what the shoes cost, but I would think that if you think they're worth saving, a cobbler could remove and replace the insole.