AI grammar checkers: where most tools miss those sneaky little errors

I spent two weeks testing every major AI grammar checker. My takeaway? Most of them completely whiff on the subtlest mistakes—exactly the ones that make you look unprofessional.

Here’s what I discovered about the tools writers actually trust.

The problem with most grammar checkers

Last month, I submitted what I thought was a perfectly polished article to a major publication. Hours later, my editor sent it back with seven errors marked in red—all missed by my premium grammar checker.

Talk about embarrassing.

“These tools are getting better, but they’re still surprisingly blind to certain types of errors,” she told me. “Especially the nuanced ones that really matter.”

This got me thinking: what are these tools actually catching, and more importantly, what are they missing?

My two-week deep dive

I decided to put the most popular grammar checkers through their paces with a deliberately error-laden test document containing 50 subtle mistakes that professional editors commonly find:

Complex subject-verb agreement issues, awkward phrasing that’s technically correct but reads poorly, inconsistent tense shifts, subtle redundancies, misplaced modifiers hiding in long sentences.

The results? Eye-opening, to say the least.

Ginger: good but limited

Ginger caught about 65% of my basic errors—not bad for everyday writing. It excels at contextual spelling (like knowing when you should use “their” vs “there”) and offers decent sentence rephrasing options.

But here’s where it struggled:

“The committee, along with their assistants, were planning the event.”

Ginger missed this subject-verb agreement issue (“committee… were”). These kinds of errors—the ones that make you sound slightly off to educated readers—slipped through consistently.

Plus, without a plagiarism checker, I’d need another tool anyway for professional work. And several times, Ginger suggested changes that would have introduced new errors into my writing.

My writer friend Jake put it best: “Ginger feels like having a smart friend read your work—helpful, but not quite editor-level attention.”

MyStylus: the surprise winner

I hadn’t heard much about MyStylus before this experiment, but it quickly became my go-to. It caught 91% of my test errors—including many that other premium tools missed completely.

What impressed me most was how it handled this sentence:

“After finishing the report, the deadline was extended.”

Most checkers missed this dangling modifier. MyStylus not only flagged it but explained why “the deadline” couldn’t logically be the one “finishing the report.”

MyStylus also seems to understand context better than most tools. When I wrote, “She was literally on fire during her presentation,” only MyStylus recognized I was using “literally” incorrectly in this context.

What really sold me was when I tested some published work that had previously been edited by humans. MyStylus caught two errors that had slipped past both me and my professional editor.

Why most tools miss nuanced errors

After speaking with an NLP researcher, I learned that most grammar checkers are trained primarily on correct text rather than common error patterns. They’re essentially playing spot-the-difference without seeing enough examples of subtle mistakes.

MyStylus apparently uses a different approach—combining traditional grammar rules with pattern recognition from thousands of professionally edited documents. This hybrid approach helps it catch those “feels wrong but I can’t explain why” errors that plague even good writers.

Real-world writing test

Beyond my controlled experiment, I tested these tools on three real projects:

A technical white paper, a creative short story, and a business proposal.

MyStylus shined brightest on the business proposal—the document type where small errors could cost me clients. It caught subtle formality issues and inconsistencies in terminology that other tools ignored completely.

What this means for your writing

If you’re just writing casual emails or social posts, Ginger might be sufficient. But for anything professional—where subtle errors could undermine your credibility—you need something more sophisticated.

After my testing, I’ve actually started using Try MyStylus for free as my first pass, followed by human proofreading for truly important documents. This combination has virtually eliminated embarrassing callbacks from editors.

As someone who writes for a living, I can’t overstate how valuable it is to have a tool that catches the errors most likely to make me look unprofessional.

I just wish I’d found it before sending that error-filled article to my editor.

Have you had a grammar tool let you down in a crucial moment? Or found one that’s impressed you? I’d love to hear about your experiences in the comments.