Overly expressive words like "robust" and words that would appear in the thesaurus for "extremely" seem like tell tale signs in my experience. I've noticed personally that sometimes I have to tell ChatGPT to "sound more human and concise." I'd love to hear if anyone else has had the same experience as me.

Regardless, if ChatGPT is tailored enough, or a custom model is created, I can't think of any way to detect if an LLM has authored something generic. The lazy college student will probably get caught, but the cunning one not so much.