Or, you know, maybe not.
Especially since the preceding description is a whole blurb about how they are utterly amoral and show nothing comparable to human emotion:
- Morally Repugnant: Every Sload individual encountered has been a grasping, callous, godless, self-loving schemer. They do not seem to experience or display any familiar human emotions, though they are skilled diplomats and actors, and produce gross, exaggerated parodies of human behavior [laughter at lame jokes, weeping at apparent misfortunes, furious tirades at folly or ineptitude]. They have no compunctions about blasphemy, theft, torture, kidnapping, murder, or genocide. They break laws whenever they calculate it in their best interests. They do not perceive or honor friendship or loyalty in the familiar human terms, except for a cheerful affinity for those who defeat them or trick them in any endeavor.
I must have missed the bit where the Thrassian Plague was started over soap.
I always figured it was a kind of secretion myself. Sload are amphibious/aquatic. Immature organisms in such environments often have "escape" instincts that involve irritating or bad tasting substances. Soap is a sure-fire way to kill any fish that wants a nibble, especially if it is concentrated, and "squirted" out.
I could easily see the sload scooping up babies by the jillions, suspending them over a pot, and torturing them so that they squirt out soap, then letting them go again afterwards-- Cooking down the juice and packaging it as soap, and selling it in exchange for corpses.
It could also be the left overs from molting, or pupation. It is never elaborated, except that "It is made from baby sload."
The main reason why I think baby mashing isn't likely, is because there would be poor consistency of product, and the product would contain little bits of macerated sload. Yuck.