Google’s September 2026 spam update began rolling out on September 24, in every language and region. The company says the rollout may take up to two weeks, making it the longest release window of the year so far.
The system behind the demotions
SpamBrain is Google’s machine-learning referee for search spam. It scores pages, hosts and domains against the company’s published policies and can demote content, remove it entirely, or neutralize manipulative links. Google has described it as “our AI-based spam-prevention system.”
Scale is the reason it exists. Google says its systems find 40 billion spammy pages every day, far beyond what any human review team could handle. SpamBrain automates the bulk of that filtering, and its verdicts feed directly into ranking.
Leaked Content Warehouse API documentation, confirmed by Google in May 2024, lists SpamBrain scores on a 0-to-1 scale at page, host and domain level. Google warned against reading too much into that out-of-context material, but it confirms scoring happens at multiple levels.
Since December 14, 2022, the system has also evaluated both sites buying links and sites passing them. Once Google neutralizes a spammy link, the ranking benefit it produced is gone, and Google’s documentation says it “cannot be regained.”
Why this hits budgets, not just rankings
Paid link spend is the first exposure. If a sponsored article or affiliate placement isn’t marked with rel=”sponsored” or nofollow, SpamBrain can strip its ranking value—quietly and permanently.
Ad-funded publishers feel the next hit. During the August 2025 update, affected publishers reported traffic declines of 70% or more. With no Search Console notice and no appeal, teams lose days just diagnosing the drop.
The territory expanded again on May 15, 2026, when Google said its spam policies apply to generative AI responses in Search. AI Overviews and AI Mode now sit inside the same enforcement perimeter, so listicles built to seed brand mentions into AI answers carry new risk.
Opacity remains the central complaint. Google doesn’t say which policy triggered a demotion. When the March 2026 core update started three days after a spam update, practitioners struggled to separate quality signals from spam enforcement.
Former search quality team member Pedro Dias described the manual review queue this way: “Low effort, high monetization intent, when these two things come together, that often signals towards something wrong.”
What to audit before this rollout ends
- Add rel=”sponsored” or nofollow to every paid and affiliate link you control.
- Review thin, scaled, or expired-domain content against the three 2024 spam policies.
- Check whether your brand mentions in AI answers could look inauthentic.
- If visibility drops, separate spam-update effects from overlapping core-update effects.
SpamBrain runs continuously; an announced update is only the visible shipment of a new classifier. Recovery still depends on Google’s systems learning over months that a site complies again. That makes prevention the faster play.
Source: PPC Land
