"Do you prefer imperfect human writing or AI writing?" is a question that is loaded.

It's absolute horseshit (and I would say somewhat sociopathic) to try to A/B test that to catch people out as if to say "aha you are lying to yourself because you can't tell".

People's preferences are representative of their desires and aspirations, their future self-perception, their better self, etc. I'm sad that you seem to think that is something they should be disabused of by statistical means.

It would be misanthropic to assume that because people say they want healthier food but then don't buy it, that they don't really want it. The proper response to that is not to give people what their behaviour says they will actually buy; it is to broadly compel food producers to make healthier food that matches what they wish they would more often choose.

ETA: above all what I want to impress upon you is that "people are really good at lying to themselves" is not actually a statement of fact; it is your opinion and interpretation projected onto the data you choose. There are other ways to explain this gap that do not involve fundamental attribution error.