The tell tell sign for me is that it's still incredibly hard to read. AI tend to write in a style that I'm unable to easily read (humans does that as well sometimes). I constantly have to go back and re-read the previous sentence, because the text simply doesn't register.
A next step I'd suggest is asking the LLM to use shorter words when available.
A next step I'd suggest is asking the LLM to use shorter words when available.