I think I'll translate this question a little so that you can get more help:
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The question:
Is the phrase "cook up" complimentary or derogatory?
This phrase means "to make something up".
But in this sentence it goes, "He cooked up a wonderful way to surprise his wife."
Now I'm confused. Is it good or bad?
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My answer:
The way I see it, when we "cook up a plan", we very often do it secretly. It is the stealth in it that goes against the belief that sees honesty as a virtue.
So if you ask me, the overall meaning of your sentence is still complimentary despite the fact that "cook up" is derogatory.
我的看法是:
我們在「設計個局 cook up a plan」的時候,常常是秘密進行的。就是這份偷偷摸摸違反了視誠實為美德的信仰。所以依我看,你這句的整體意義是好的,雖然 cook up 本身的意義還是壞的。