I found that many people don't have a radar for this. They may know about delve, emdashes, tapestry, multifaceted or "not just X but y" and if these are not there they don't see it.
I think those who are very opposed to AI often don't know much about the real limitations since they don't use it, and their complaints are often a year or more out of date.
I think the ideal demographic for spotting these are people who use the frontier LLMs a lot and they also have worked with text in detail, such as copywriters, people who have learned foreign languages and grammar etc., have edited articles for language and generally have a more "wordsmith" look at language and are sensitive to flow and rhythm of language on a more technical level.