If someone tries to hide that their writing contains AI, or otherwise gets their AI to write differently through prompting or a special model, I can’t tell. I can suspect through heuristics, like perfect grammar, rule of three, bad metaphors, vapidity (which is a particularly strong signal), and a hard-to-describe “feeling”. But some people write like that, especially if they've read lots of AI writing themselves; and the same phrase (especially if it's short) can have been generated by AI and written by a human.
However, I’ve noticed a lot of writing where it seems the person and model don’t even try to hide that it’s AI. Besides matching every heuristic above and an especially strong AI “feeling”, there are literal giveaways: “it’s not X, it’s Y”, “here’s the kicker”, “quiet part out loud”, “and the best part?” While technically a human can write like that (e.g. if they pretend to be AI), I feel it’s safe to assume such writing is at least AI-assisted.
Ultimately though, I always judge writing on the content itself and recommend you do too. Every piece of writing that I’ve known or suspected was mostly AI-generated has been long-winded and vapid, which AFAIK most people consider to be valid criticisms, so you're less likely to get pushback for claiming them. And at least for me, it’s easier to determine and prove that writing is long-winded and vapid than AI-generated. If a piece of AI writing is terse, informative, and high-quality in other ways, personally I would consider it high-quality overall (and I’ve already judged some writing as high-quality that I later learned was AI assisted, but it ended up being mostly human-written with the AI only rephrasing a few small parts).
Rather than relying on simple regex matches for words like “delve” or checking for em dashes, the heuristic I used was this: if someone asked me to convince a friend to read a given story in a single sentence, could I do it?
I find that once you strip away much of the decorative finery from AI-generated copy, it just doesn’t have much to say. AI often tries to distract from its prosaicism with reams of descriptive prose.
[1] - https://mark---lawrence.blogspot.com/2023/09/so-is-ai-writin...
You usually can’t prove it instantly—but you can smell it fast. AI writing leaves fingerprints. Here’s the blunt version.
First: it sounds correct but feels hollow. The sentences are clean, grammatical, and oddly polite. Nothing risks being wrong. Humans leave dents—opinions, hesitations, slightly ugly phrasing. AI sandpapers those off.
Second: too balanced, too fair. Every argument has a counterargument. Every claim has a caveat. Real people pick sides, forget disclaimers, or double down when they shouldn’t. AI keeps the peace like it’s being graded.
Third: generic confidence. It explains things with authority but without lived detail. No concrete scars, no oddly specific anecdotes, no “this broke in production at 2am” energy. It knows about things, not through them.
Fourth: structure over voice. Paragraphs march in neat formation. Transitions are impeccable. You could reshuffle them and nothing would change. Human writing has rhythm problems and obsessions—it lingers where it shouldn’t.
Fifth: vague specificity. Phrases like “various factors,” “a range of considerations,” “it’s important to note.” These say nothing while pretending to say something. Humans usually either ramble or overshare instead.
Sixth: no genuine surprise. AI rarely startles you. No sharp metaphor that makes you pause. No sudden pivot that reveals the writer’s personality. Everything feels anticipated.
Seventh: the absence of stakes. There’s no sense that being wrong would matter. Human writing often leaks anxiety, pride, frustration, or desire. AI writing feels emotionally insured.
Important caveat: good human writers can sound “AI-like,” and skilled humans using AI can mask it well. Detection isn’t a switch; it’s a pattern-recognition reflex. You’re not spotting a robot—you’re noticing the lack of a human fingerprint.
The deeper truth is uncomfortable: as AI improves, the tell won’t be style—it’ll be experience. Writing grounded in real constraints, consequences, and tradeoffs will remain the hardest thing to fake. That’s where humans still leave marks that aren’t easy to erase.
AI written text is often characterized by a very peculiar choice of words — many people report "delve into" is a particularly telling sign of text written by AI.
If you want me to add more examples, feel free to ask me for more!