It has nothing to do with cleanliness. In fact too much washing will cause more irritation and dry flakes.

Some moisturizers don't last the whole day and flaking starts again midway through.  My samples of Physiogel -- both types are long lasting and help control flaking. I suspect the "Rich" formula will be better because it is thicker and one ingredient is "ceramide" which is a promising new substance found in expensive oral skin supplements (Eliz Arden $300)
It claims to form a skin barrier, so probably good for using under cosmetics to conceal. Ask for samples to try before buying the small tube at Rm60! Remember, moisturizing is not a cure!

Many will say eat this, don't eat that, take vitamin X. All of these are unproven, especially if you are looking for quick results. Another theory is that Seb Derm lives on oil, so they say don't use anything oil based, not even soap. That may be why sea salt works for some people. It might just be that all salts tend to calm irritated skin.

Things that have NOT worked, meaning still have SD or it continues to spread (in other words, waste of $$$) :

H&S (pyrithione), Selsun (selenium sulfide), Coal tar soaps, raw honey, cider vinegar, Cetaphil.
Antifungal creams, steroids, acne creams, Elidel cream (tachrolimus, powerful prescription)

We must face the possibility that it is a genetic hereditary or immune condition that is affected by tropical climate.