Why AI Detectors Flag Your Writing (and How to Fix It)

What AI Detectors Actually Measure

AI detection tools aren't reading for meaning. They're measuring statistical patterns that differ between human and machine writing, and they're better at it than most people expect.

The two main signals are perplexity and burstiness. Perplexity measures how predictable each word choice is. AI tends to pick the most probable next word, which makes the text feel smooth but statistically flat. Burstiness measures variation in sentence length. Humans write in bursts: short sentence, then a longer one that builds context, then short again. AI writes in steady, even rhythms. That even rhythm is the giveaway.

The Vocabulary Patterns That Read as Robotic

Beyond sentence length, detectors look for word-level patterns. Certain phrases show up in AI-generated text at a much higher rate than in human writing, so they've become an easy tell.

Some of the most common ones: "it's worth noting", "it's important to", "in conclusion", "delve into", "navigate", "landscape", "pivotal", "seamlessly". These aren't wrong in isolation, but when they stack up together, the writing starts to sound like a template rather than a person.

Other patterns: always starting sentences with "The", using "ensures" repeatedly, heavy reliance on passive voice. Real people write more chaotically than that.

How to Make AI-Assisted Writing Sound Like You

A few concrete writing changes make text read naturally instead of sounding like a template.

• Break the sentence rhythm.Write a short sentence. Then write something longer and more detailed that adds context or nuance, the kind of aside that only comes to mind when you're actually thinking through a topic. Then go short again.
• Swap the cliché vocabulary.Go through the text and find every word that sounds like a corporate memo. Replace "utilize" with "use". Replace "leverage" with "use". Replace "facilitate" with "help". Simpler reads as more human.
• Add a specific detail only you'd know.AI writes generically. Humans reference specifics. Drop in a number, a real name, a concrete example. "We increased signups by 23% in Q3" reads very differently from "we improved our conversion rate significantly."
• Use contractions.AI defaults to formal, contractionless language, even when you ask it not to. Don't, it's, you'll, I've: these all read more like natural speech.
• Start sentences differently.Check the first word of each sentence. If five of them start with "The" or "This", rewrite some. Varied sentence starters are a natural human writing habit.

What Not to Bother With

A few popular shortcuts aren't worth your time. Invisible characters or Unicode tricks don't fix the underlying writing. Paraphrasing tools help a little with surface-level patterns, but they don't fix flat, predictable phrasing. And simply prompting an AI tool to "write more like a human" doesn't do enough. It still defaults to the same flat rhythm, no matter how you phrase the instruction.

The thing that actually works is real editing. Rewrite the giveaway sentences. Add specificity. Break the rhythm. It takes 10–15 minutes per page, but it's the method that holds up consistently.

For Cover Letters Specifically

Some hiring teams are paying closer attention to whether a cover letter reads like it was actually written by the applicant. If you're using an AI tool to draft your cover letter, the step where you make it sound like you isn't optional.

SleevIx builds that step in. The output goes through a pipeline that adjusts sentence length variation, replaces the vocabulary patterns above, and adds specificity based on the job description, so you get something that reads naturally, not like it came out of a model.

Want to understand what makes a cover letter itself effective? Read our guide on how to write a cover letter that survives the 7-second skim.