The em dash panic: how one punctuation mark became an AI tell
The — em dash is not evidence of anything. Models reach for it because edited prose is full of it, and plenty of humans write that way unassisted. What it does do is read as machine-drafted to a lot of people in 2026, and it rarely arrives alone: curly quotes, a real ellipsis character and invisible spacing usually come with it.
How a dash became a tell
Large language models trained on edited, published prose: books, journalism, long-form essays. Edited prose loves the em dash, so models reproduce it generously. By early 2025 readers had noticed the pattern, and through that year the reaction escalated from observation to allergy.
The complaint was never that models used em dashes. It was that they would not stop. Users reported that explicit "do not use em dashes" instructions were ignored, which is what made the mark feel like a fingerprint rather than a style choice. OpenAI eventually treated it as a product problem and announced in November 2025 that custom instructions to avoid the character finally work. The default behavior still reaches for it, and by then the cultural damage was done.
Is the em dash actually proof of AI?
No. Researchers who study machine-generated text keep repeating the boring version: the character shows up in model output because humans wrote that way in the training data. Treating one character as a verdict misfires constantly, and it misfires hardest on the most well-read writers.
"Not proof" is not the same as "not a signal people react to", though. Perception runs ahead of statistics. An em dash in a cold email, a product review or a social post now gets read through a filter it did not face three years ago.
The dash rarely travels alone
The dash gets the headlines, but pasted AI text usually carries a whole typographic accent:
Curly quotes instead of straight ones, a true ellipsis character instead of three periods, occasionally styled Unicode letters, plus an invisible layer of non-breaking and narrow no-break spaces you cannot see at all. Any one of them is innocent. Together they read as a paste from somewhere else.
What to actually do
If you love the em dash, keep it. Write like yourself. The mark is innocent, and surrendering good punctuation to a moral panic is a sad trade.
If you use AI tools while drafting and want the output to read as yours, normalize the typography instead: em dashes to plain dashes, curly quotes to straight, the real ellipsis to three periods, and strip the invisible passengers while you are at it. Doing that by hand on every paste is a chore, and doing it through a web tool means mailing your drafts to a stranger to solve what is fundamentally a privacy problem.
The right place for the fix is the clipboard, because that is the one checkpoint every paste passes through, whatever app the text came from and whatever app it is headed to.
Text cleaning is coming next to tdy.
tdy is a Mac menu-bar app that already tidies every link you copy. Normalizing AI typography and stripping invisible characters is the next upgrade. One email when it ships, nothing else.
Join the launch list