The em dash is an AI fingerprint
Readers and editors have started using a run of em dashes as a quick check for AI writing. It is not proof on its own, but combined with even, hedged phrasing it is a strong signal.
The reason is simple: people rarely type em dashes. They are hard to enter on a normal keyboard, so most human writing uses commas, periods, or plain hyphens instead. A model has no such friction.
Why models love the long dash
The em dash is grammatically flexible. It can stand in for a comma, a colon, parentheses, or a full stop, so it is a low-risk choice that almost always fits. Trained on large amounts of edited prose, where the em dash is common, models reproduce it heavily.
The result is text that is technically correct but unmistakably even and machine-paced, with dashes where a person would have varied the punctuation.
How to remove em dashes cleanly
Replacing every dash by hand is tedious and easy to miss. A cleaner does it in one pass, swapping each em dash for the punctuation that fits the sentence, usually a comma or a period, and a plain hyphen where a connector reads better.
Run the same pass to strip any leftover Markdown and formatting, and the text reads like it was written by a person, not assembled by a model.
It was a good idea — maybe the best one — but the timing was wrong — so we waited.
It was a good idea, maybe the best one, but the timing was wrong, so we waited.