This is abstract, I know. So let me make it clear.
Take the sentence, "Don't step on that landmine."
My experience says most clients would call that sentence "negative," and ask you to change it, partly because it starts with the word "Don't" and partly because it contains the word "landmine."
You try to explain that "don't do something negative" is a positive. But they can't seem to understand that.
So you rewrite it. "Step anyplace you like. But your day will be sunnier if you avoid that anti-personnel device."
They come back with feedback like this. "I like the first sentence, it's empowering. However the second sentence starts with a negative conditional (but) and contains the phrase "anti-personnel," which will probably not get through HR and will test poorly.
You put your nose to the grindstone. "Step anyplace you like. And try to avoid that section which is less than ambient."
Their feedback? Better. But they're still tripping over the negativity of "less than ambient" and the word "avoid," which is also negative.
At this point, it's late, and well-past the time you should be home for what they pay you. So you send back the following: "Have a nice day! :)"
"You've nailed it," they say. "This is great! Thank you!"