I've seen skills on the various skillz marketplaces that specifically instruct the LLM-generated text to replace emdashes with hyphens (or double-hyphens), and never to use the "it's not just <thing>, it's <other thing>" phrasing.
Also to, intentionally introduce random innoccuous punctuation and speling errors.
Also to, intentionally introduce random innoccuous punctuation and speling errors.