JonnyHK 

Here's the deal. Have always dripped sweat while working hard and now I live in the tropics (summer hasn't even started yet), so the bike always gets a good soak as I drip on it.

The sweat that hits the top tube then runs underneath to the rear brake cable and the cable stops. My cable has gone a bit skanky black looking in parts and the cable stops build up a scunge of salt.

I do wipe down the bike with a damp cloth and some spray kitchen cleaner after each ride as part of my routine, but should I do more? I'm thinking that I need more water to dilute out that salt. Should I treat the cable with something (soak it in an oil or protectant)?

I'm going to replace that cable soon, but I think I'm going to get some alloy corrosion soon on the frame (CAAD 9) around those cable stops.

Any advice or experiences that might help?

nitropowered

put a towel over your toptube and bars when you ride. It'll keep the sweat from hitting your bike directly

rOOster14

while having a towel on your stuff is practical indoors, outdoors it really isnt.

as far as keeping your bike in good shape to combat your sweat, i would encourage doing what you are doing, but making sure you take the cable housing/ferrules out of the bosses regularly. that is the biggest problem i ahve seen with sweat corrosion is that the ferrules and bosses can practically weld together. aside from that, regularly dropping a bit of lube into the ferrules where the cable comes out with a needle luber or applying a liberal amount of slick honey when you replace the cable (do it twice a season instead of once...depending on how much you ride).
all this should keep you in good shape, keep wiping down the frame, and sweat on haha.

wanders

all what rooster said and you might try boeshield.