Why Does My Writing Sound Like AI? 5 Signals to Self-Diagnose

The short answer: it's not one thing, it's a pattern stack

Ask "why does my writing sound robotic" and you will get vague advice — "be more conversational," "add personality." Useless, because you cannot edit a vibe.

Here is the useful version. AI-sounding prose is a stack of five overlapping habits. Each one alone is survivable. Stacked together, they read unmistakably like generated text.

• •Slop vocabulary — a cluster of words LLMs reach for far more than humans do.
• •Cliché phrases — prefab openers and transitions that carry zero information.
• •Uniform structure — sentences and paragraphs that are all the same length and shape.
• •Low word variety — the same words and bigrams recycled, or the opposite, an oddly even spread with no favorites.
• •Thin substance — text that could be about anything because it names nothing.

The rest of this article walks each one. Diagnose them in order; most drafts fail on two or three, not all five.

1You're using the "AI vocabulary"

Why it reads like AI: Certain words spike hard in AI output, not because they are wrong, but because models over-select them. When your draft is dense with these, readers who have seen a lot of ChatGPT text pattern-match instantly.

The cleanest evidence comes from academic writing, where the shift is measurable. A 2024 study of 14.2 million PubMed abstracts found that after ChatGPT's release, a specific set of style words — not content words — jumped in frequency, with the authors estimating at least 13.5% of 2024 abstracts were processed by an LLM (Kobak et al., Science Advances, 2025). Florida State University researchers Tom Juzek and Zina Ward traced the most notorious offender — delve — and found people react "much more negatively" to it than to other buzzwords (FSU News, 2025). Their explanation is the interesting part: the overuse traces back to the human-preference training step. Raters rewarded this register, so the model learned to produce more of it.

Words that repeatedly show up as tells: delve, realm, intricate, tapestry, testament, leverage, utilize, seamless, robust, multifaceted, underscores, elevate. The SlopDetector engine sorts them into three tiers — "kill on sight" words that almost never appear in natural writing (delve, tapestry, myriad, plethora), words that are fine alone but slop in clusters (robust, seamless, leverage, cutting-edge), and light signals that only matter in bulk (crucial, essential, furthermore, moreover).

The measurable version: the engine counts weighted hits per 100 words. One delve in a 1,000-word essay is nothing. Three "kill on sight" words plus a scatter of tier-two words in a single paragraph pushes the vocabulary score toward its ceiling — the density where a reader thinks, "wait, is this AI?"

Fix it: Do a find-and-replace pass for the tier-one list. Swap for the plainest word that means the same thing.

The second sentence is shorter, says more, and names something real. That is not a coincidence — the slop words were doing the work of sounding substantive while the sentence said nothing.

2Your phrasing is prefab

Why it reads like AI: Whole phrases — not just words — are giveaways. "In today's fast-paced world," "it's important to note that," "when it comes to," "studies have shown," "let's dive into." These are structural filler. They occupy the space where a real idea should be, and models deploy them constantly because they are safe, grammatical, and content-free.

This is different from Signal 1. A single word can be innocent; a cliché phrase almost never is, which is why the engine scores it more aggressively. One textbook cliché already registers as a strong tell (8 out of 20 on its own), because a phrase like "in today's rapidly evolving landscape" essentially never survives an edit by a writer who is paying attention.

The tell has three flavors, and it helps to know which one you lean on:

• •Prefab openers: "In a world where...", "Picture this...", "Ever wondered...". They stall before the sentence starts.
• •Fake authority: "Studies have shown...", "Experts agree...", "Research suggests..." — with no study, expert, or citation named. Ironically, this is the exact move that makes text less credible, not more.
• •Empty transitions: "That being said," "At the end of the day," "It goes without saying." (If it goes without saying, cut it.)

Fix it: Delete the phrase and see if the sentence loses anything. Almost always it does not.

Same length, but one of them names a source and a finding. Fake authority becomes real authority the moment you name the study — and if you can't name one, that is a signal your claim needs support, not a fancier phrase.

3Every sentence is the same length

Why it reads robotic: This is the deepest one, and it is why "why does my writing sound robotic" is a better question than most people realize. Human writers vary their rhythm without thinking. A punchy four-word sentence. Then a longer one that winds through a couple of clauses before it lands. Then something medium. Models, by default, produce sentences of eerily consistent length and shape.

AI-detection tools have a name for this: burstiness. GPTZero defines it as "how much writing patterns and text perplexities vary over the entire document" — humans vary their patterns constantly, while models hold a steadier level, so generated text scores low (GPTZero, "Perplexity and Burstiness"). Human writing is bursty: short, long, medium, short. Generated text tends to be flat. The SlopDetector engine measures one concrete slice of this — the variation in your sentence lengths (the standard deviation divided by the mean, called the coefficient of variation). The threshold is specific: when it drops below 0.15, sentence lengths are "suspiciously uniform" and the structure score jumps.

Two related tics live in this signal:

• •Transition-opener addiction. When half or more of your sentences start with However, Furthermore, Moreover, Additionally, Consequently, it reads mechanical. The engine flags it when the ratio crosses 50%.
• •Em dash overload. The em dash became so tied to ChatGPT it earned the nickname "the ChatGPT hyphen" (Rolling Stone, 2025). McGill University's science office traced why: the em dash is a clean tool for inserting an explanatory aside, and clarity is exactly what these models are tuned to produce (McGill OSS). It got bad enough that in November 2025 OpenAI's Sam Altman announced a fix, saying that if you tell ChatGPT to avoid em dashes, "it finally does what it's supposed to do" (TechCrunch, Nov 14 2025). The engine starts docking points above two em dashes per 100 words. (The mark itself is fine — the tell is density, not the punctuation.)

Fix it: Read your draft aloud. Where you never pause, break a long sentence in two. Where three sentences march in step, fuse two of them or chop one to a fragment. You are manufacturing burstiness on purpose.

4Your word variety is off — in either direction

Why it reads like AI: This one is a two-sided trap, which is why people miss it. The obvious failure is too little variety: you lean on the same handful of words and two-word phrases, and the text feels padded. The engine measures this with the type-token ratio (TTR) — unique words divided by total words. On a sample of 35+ words, a TTR below 0.4 flags as "very low vocabulary diversity."

The non-obvious failure is too much variety. Language models draw from an enormous vocabulary and rarely repeat a word, so genuinely human prose — which usually leans on a few favorites — almost never sustains a TTR above 0.88 past 50 words. An unusually high turnover is itself an LLM tell. Real writing has texture: a couple of words you overuse, a rhythm of repetition. Perfectly even distribution reads synthetic.

The engine watches two supporting tells:

• •Repeated bigrams: the same two-word pair ("meaningful results," "key driver") three or more times.
• •Intensifier density: very, truly, highly, incredibly, remarkably, deeply, profoundly stacked up. Above 3% of your words it flags. Intensifiers are the calorie-free sweetener of prose — emphasis without meaning.

Fix it: For low variety, vary your nouns and verbs; stop restating the same idea in the same words. For suspiciously high variety, relax — let a strong word repeat instead of reaching for a thesaurus synonym. And cut the intensifiers wholesale; "remarkably effective" is just "effective" wearing a hat.

5It could be about literally anything

Why it reads like AI: This is the one that matters most, and the hardest to see in your own writing. Slop is substitutable: swap the topic and every sentence still works. "In this ever-changing landscape, success requires dedication and a willingness to adapt." That sentence fits an essay on marketing, gardening, or nuclear physics. It is content-shaped, but it contains no content.

The engine checks substance three ways, and you can run the same checks by hand:

1. Specificity. Does the text contain concrete numbers, dates, proper nouns, or references? Text with none of these gets the maximum substance penalty. Naming things (a date, a dollar figure, a person, a place) is the single fastest way to sound human, because generation defaults to the generic.
2. Substitutability. Vague subject-fillers — "this topic," "this field," "the modern world," "the landscape," "our society" — are the seams where interchangeable text shows. Three or more and the engine flags the whole passage as generic.
3. Platitude endings. "The possibilities are endless." "Only time will tell." "The future is bright." A closer that could end any article at all is a closer that ends nothing.

Fix it: For every vague claim, ask "according to what? how many? which one? when?" Replace one abstraction per paragraph with a specific.

The second version names a product, a year, a number, and a stake. It could not be about gardening.

Put the five together

Here is the whole diagnostic in one place. Run down it and mark where your draft fails:

There is a through-line here. Signals 1, 2, and 4 are about word choice — you are reaching for the register readers associate with generated text. Signals 3 and 5 are about rhythm and substance — the text is flat and could be about anything. Most drafts that "sound like AI" fail a couple in each group.

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