AI writing often feels too smooth, too even, and too positive
A review of about 89,239 Reddit posts from 2021 to 2026 looked at what makes people think a piece of writing was made by AI. After , 7,984 posts were directly about spotting AI writing, across AI tools, writing, and SaaS discussions. The clearest signal was heavy use of the em dash.
Other common signals were sentence rhythm that feels too flat, a tone that stays unnaturally positive, and paragraphs that look polished but do not say much. These clues are easy for human readers to notice, but hard for software to measure. That makes difficult when it depends only on checks.
The analysis used shares of relevant posts instead of raw counts because the topic grew sharply, from 26 relevant posts in 2021 and 86 in 2022 to 587 in 2023 and 3,174 in 2025.
Key points
- About 89,239 Reddit posts were reviewed, and 7,984 were directly about spotting AI writing.
- Heavy em dash use was the most obvious signal mentioned.
- Flat sentence rhythm and constant positivity made writing feel more AI-made.
- Polished paragraphs with little substance were another common warning sign.
- Human readers rely on clues that often cannot measure well.