[leftcoaster]

Grammar is about sentence structure; your point is about word choice, otherwise known as "diction."

And "flush" is perfectly correct. Used transitively, it means "to expose or chase from a place of concealment." Example: "the hunters used dogs to flush their game from the bushes."

In figurative language, "flush" is a good choice when you're talking about stripping away extraneous information. "Flesh" is used when you're proposing to add more information, as in putting flesh onto bones.

I should add that I'm only addressing your claim that "flush" is inherently scatalogical, not whether the original use was valid.