I use the thick "Bore Stores" soft gun sleeves. They are impregnated with silicone, and supposedly help draw any moisture away from the firearm. I have never have a problem with any of my long guns, if I store them in Bore Stores.
Scopes bring in the light which can help you in low light conditions, like the last five minutes of legal hunting time. Last deer I took was with a muzzle loader, but had I not had a scope on it, I would not have been able to be as sure of my shot as well, as it was getting darker. Had a not...