Usually the smell is when it sounds profound or insightful but then you realize it's word salad and not really saying anything. LLMs also try to make the most mundane thing sound revolutionary or write about it in an alarmist way like 'increasing x by 1% is a ground breaking innovation' or something.

There's no concept of what truly is important with the writing itself since there's no actual thinking going on. The opinion of the supposed writer, which colors how they structure the writing and the language they use, is often all over the place since an LLM has no real opinions.

https://en.wikipedia.org/wiki/Wikipedia:Signs_of_AI_writing

It's the cadence and the density of cliches. I've seen Opus produce very similar output. That's not to say it's 100% that this was written by an LLM. They had to learn this style from human writing in the training data. It's just a very condensed form of bad writing.

fwiw Pangram says 100% of the original article was written by AI