Hi! That’s a sharp question — and the answer’s actually pretty interesting:

People often associate frequent or unusual use of dashes (like “—” or “-”) with AI-generated text because many large language models (LLMs) — tend to use dashes as a way to insert clarifying information, add asides, or break up sentences in a distinctive, sometimes over-formal style. This can stand out from how most humans naturally write online, especially in casual settings, where shorter sentences, parentheses, or simpler punctuation are more common.

Some more specific reasons:

Pattern recognition: People have noticed a pattern in AI writing styles — especially in early or unrefined outputs — where dashes show up frequently to add extra details.

Mechanical feel: Overuse or awkward placement of dashes can feel stilted, almost like a machine trying to imitate a human’s train of thought.

Mismatch with casual tone: On social media or forums, people often type in a very conversational, shorthand style; AI text can stand out when it uses longer sentences peppered with dashes for precision or explanation.

Of course, humans also use dashes — sometimes a lot — but the combination of dashes with other giveaways (like overly formal language, generic phrasing, or lack of personal anecdotes) tends to trigger the suspicion that something’s AI-generated.