That's the problem with AI writing in a nutshell. In a blind, relatively short comparison (similarly used for RLHF), AI writing has a florid, punchy quality that intuitively feels like high quality writing.

But then after you read the exact same structure a dozen times a day on the web, it becomes like nails on the chalkboard. It's a combination of "too much of a good thing" with little variation throughout a long piece of prose, and basic pattern recognition of AI output from a model coalescing to a consistent style that can be spotted as if 1-3 human ghost writers wrote 1/4 of the content on the web.