How does gumbo spoil while still cooking?

I believe in this context, spoil is not referring to food safety issues such as dangerous pathogens, but rather that the dish does not fulfill its culinary promise.

For example, any soup or stew that is cooked on too high a heat will become burnt on the bottom. You won't get sick from eating it, but from a flavor aspect, it's spoiled.

Not being an expert in cooking gumbo, I can't cite all the specifics, but there surely is an optimum heat and time that it should be cooked. Stray too far from the base recipe and technique, and you may spoil the gumbo.

From your comments, it sounds like the recipe calls for cooking the gumbo to a point of "doneness", and then turning down the heat so that it stays below the boiling point. In other words, if the fully cooked gumbo continues cooking at a full boil, the recipe will be spoiled.

"Spoiled" is a common term used for judging whether food is fit to eat. It is supposed to apply to food which is full of potentially pathogenic bacterial colonies, but of course, it is impossible to see bacteria.

However, there is one quite sure sign of bacteria: slime. Bacterial colonies tend to produce slime on usually-dry food items. So, people have learned to associate slime with bacteria. If somebody is not very discriminating, he or she may decide that every slimy food must be spoiled.

Gumbo frequently contains okra, one of the rare foods which releases slime when cooked. This has nothing to do with bacteria, the compounds which create the slime are produced by the vegetable itself. But as a result, you can have slimy gumbo.

Now, if you have a person for whom "slimy" is equivalent to "spoiled", either because they think that "spoiled" is the same as "dangerous" and that "slimy" is always "dangerous", or because they know the difference, but dislike the texture and feel that any slimy food is unfit for eating, it is very probable that this person will call a slimy gumbo "spoiled". Is this correct or not? For some definitions of "spoiled", it is correct, for others, it isn't.

In any case, gumbo does not become infested with dangerous levels of pathogenic microorganisms while cooked.

To answer the question in the purest sense of the possibility of it happening, I can say that gumbo will indeed be legitimately spoiled when the pot is turned off if: a) you may have used stock that was already spoiled or b) one of your seafood ingredients may have already been spoiled. By spoiled I mean stock that had been prepared ahead of time but left out over night and refrigerated 16 hours after the time it was prepared or seafood that was stored in the fridge after it had spoiled. Both have happened to me at different times unfortunately. Very expensive lessons learned.