Carefully phase in grammar checkers

[goodroi]

Most people aren't Shakespeare and could use a bit of help with content writing. There are many different browser & CMS add-ons that can help like Grammarly. Not having typos and correctly using commas will make a better impression on users which can indirectly boost many key metrics.

Before you rush off and implement this on your entire site, remember that Google tends to reward freshly updated content. What's the worry, sounds like a bigger reason to do this? Well because Google knows that we know this, they also penalize sites that abuse it. Years ago, webmasters realized that if they ran a script to make a super minor change to every article at the start of each month, they would get a ranking boost. So Google evolved to block that trick. If you add a grammar checker to your CMS and touch all your articles with super minor changes you might accidentally look like you are trying to spam the freshness booster. Safest to slowly phase it in.

Remember that part of ranking well in Google means knowing how to avoid accidentally triggering a false positive on their spam filters.

[aristotle]

If you have old articles that haven't been touched in years, and they are ranking well for their main keywords, then in my opinion you shouldn't make any changes to them at all, even if one or two words are mis-spelled..

It's best to be very careful about spelling, grammar, etc when you originally write an article.

[riccarbi]

As far as I know, Google doesn't give a damn about poor or good grammar. This would require their system to perform a grammar/typo check for every page in the index and do that for 149 languages, which is unrealistic.
About the fresh/updated/date-changed content, I don't trust Google anymore but I trust my users. Therefore, if you deem appropriate to amend a couple of grammar errors on a page because this would improve the user's experience and your content quality, just do it.

[aristotle]

riccarbi -- I agree with your view for most cases, but think there could be exceptions.

For example, suppose you have an article that ranks number 1 in google for its main keywords, and gets a lot of traffic. If you make changes, it can't go any higher but it could drop lower and lose traffic.

[iamlost]

Given the gobbledygook, often one of scraped and Google Translated or scraped and poorly mashed content, frequently served it is obvious that Google does no explicit content comprehension.

I view search results (not just G’s) as similar to the infamous ML image identification fiasco where snow in background was how the black box concluded there was a wolf in the pic.

Where good, whether proper or colloquial, use of language, including grammar, is important, depending on audience demographic critical, is in grabbing, holding, and converting those human visitors that G et al deign to refer.

Back in the heyday of MFA gobbledygook content forced users to the relatively comprehensible ads; a behaviour that is mostly less viable for less time these days. Of course, these were one time only visits, that rarely converted for the advertisers, thus why G took action.

Know your audiences and write for them in a way that converts (define as you will) for you. Don’t worry overly about G and Co. as you get them regardless.
Note: Most SEO is 99% hype a decade past sell by date.
Note: correlation is not causation, third party simulations are not reality, etc. et al ad nauseum.
Note: meaning before metric, measure before method.

[riccarbi]

riccarbi -- I agree with your view for most cases, but think there could be exceptions.

For example, suppose you have an article that ranks number 1 in google for its main keywords, and gets a lot of traffic. If you make changes, it can't go any higher but it could drop lower and lose traffic.

Right, Aristotle, your remark makes sense, definitely. Yet, to improve grammar and text comprehension can lead to higher time on page, lower bounce rate (since it's number 1, that article is very probably a landing page as well), more inbound links, and, last but not the least, higher Ad revenues. ;). Furthermore, Google often plays dirty with nr.1 pages. I have pages that had been number 1 for years and suddenly dropped to nr. 10 for no reason; and others that, without making any change, raised to nr.1. My suspect (conspiracy theory?) is that Google's algo statistically presets how many high-ranking pages a given website can have and, if high-quality pages of that site exceed the limit, rotates them periodically.

[engine]

I'm of the same opinion as aristotle, don't change content that is ranking well.
I would happily add new content.

I don't use grammar checkers (can you tell, lol) and prefer to rely on my experience.

Having said that, I agree with goodroi, any sudden changes to a whole site can make the content seem contrived: Imagine if you re-launch the site. You're in the lap of the search engine algo, and take a risk.

[lucy24]

Conclusion: If you discover a mistake on a page--be it grammar, spelling, or an unambiguous error of fact (“pi = 3.14519...”, “Mozart was born in 1856”)--you should leave the mistake uncorrected because it might harm your ranking.

I weep for the internet.

[aristotle]

You have to make sure everything is accurate and correct before you originally publish it. If there is doubt or dispute about something, you have to make that clear to the reader.

[tangor]

As part of my copyright protection against scrapers I DELIBERATELY insert at least TWO "errors" which the human reader will forgive when reading the content to make it easier to identify theft. The inverse of that is who to SUE (those scrapers who CORRECT those errors" for their site content!). You'd be surprised how well that works out.

Meanwhile, grammarly and ilk are 403'd when they come visiting.

Not suggesting any others follow my path, just revealing it on my side.