Em-dashes have become a telltale sign of AI-generated text, which has created some funny side effects.
I now frequently see correct and incorrect usage of hyphens and dashes mixed in the same piece of text. This happens when someone revises a piece of AI-generated text but doesn't understand the difference between hyphens, en-dashes, and em-dashes.
It's also pretty obvious that some people have started find-replacing all em-dashes with single hyphens (-) or double hyphens (--) to hide that they used AI. Which, of course, is its own tell.
But this still doesn't hide the most obvious giveaway, which isn't the em-dash itself. LLMs almost always put spaces around em-dashes: word — word instead of word—word. My guess is that models are heavily trained on news data, where the AP style guide, most commonly used in journalism, recommends spaces around em-dashes. Books and most professional writing use them without spaces.
So if you're taking your writing seriously, there's no way around learning how to use hyphens, en-dashes, and em-dashes correctly. I wrote a short post explaining the differences on my blog: Hyphens and Dashes
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