The only areas I spray on my reel are the bail arm pivot and guide bearing, the handles anti reverse lever etc and I only ever use Inox, I always have a small smear of inox food grade grease around the base of the drag knob which should prevent any water getting near the drag washers.
From the Inox website...
The only lubricant in the world with the special MX3 Anti-Corrosion, Anti-Moisture formula for the twenty first century (food grade approved). It displaces, penetrates, lubricates and protects. INOX contains no silicon, acid, kerosene or dieselene. INOX will not harm metal points or surfaces, plastics, paints, enamels, fibreglass, formica or neoprene seals. INOX doesn't dry out, gum up, become gooey or sticky or wash off with water! INOX is non- conductive, non-static, non-toxic, non-corrosive and non-staining.
Most other moisture displacers/lubricants are petroleum or solvent based.
I have heard of people who swear by some of these products as an attractant to fish, but I dont believe it personally, does it make a difference to catch rates? again I dont think so, having said that you have no reason to spray the spool anyway, some warm water in a hand sprayer and a wipeover with a clean cloth should be adequate.
GT