The problem is the well's been poisoned just by the fact that I know this is AI trying to hide AI, so I'm already poised to look at the examples and declare "aha! this is obviously AI!" Moreover, it's not single sentences or phrases that make AI text stick out (though obviously those are the biggest tells), it's the text taken as a whole. When you read the full output example in that repo, it seems obvious to me that it's AI (though again, it could be the poisoned well). This is the uncanny valley I was talking about; something is just off about it.