PBNs and Link Farms: How to Spot a Site Selling Low-Quality Links

PBNs, Link Farms and Toxic Sites: What Are We Talking About?

These terms cover related but distinct realities. Knowing them helps you understand what to look for when you analyse a site that is offering to sell you a link.

Private Blog Networks (PBNs)

A PBN is a group of sites controlled by the same owner, often built on expired domains that kept backlinks from their previous life. Their purpose is to pass that authority on to client sites. Owners try hard to hide the connection between sites, with different hosts, different themes and fake authors. PBNs built for resale, however, tend to leave common traces.

Link Farms

A link farm is a site or group of sites that publishes large numbers of articles whose only purpose is to host outbound links, on topics that have nothing to do with one another. No editorial line, no audience, often dozens of new articles a week. Google classifies these schemes as link manipulation.

Low-Quality or Hijacked Sites

These are sites that once had a legitimate existence and were then bought or repurposed to sell links, or sites filled with automatically generated content of no value. Since 2024 Google has stepped up its fight against site reputation abuse, expired domain abuse and scaled content abuse, three practices that are frequently associated with link selling.

Why These Links Are Risky for Your Site

The risk is not theoretical. Google has automated systems, including SpamBrain, that can identify sites selling links and the links those sites send out. The main effect of Google's link spam updates is to neutralise those links.

Silent Neutralisation

In most cases Google simply ignores links from these sites. You receive no warning: you have just paid for a link that passes nothing. For a link building budget, that is already a net loss, and it is hard to detect without proper tracking.

The Opportunity Cost

Beyond the price paid, a useless link costs you time. During the months you spend waiting for the effect of links that pass nothing, your competitors are climbing with real links. By the time you notice the lack of results, the budget is spent and you have to start over. For a small business, this hidden cost often weighs more heavily than any penalty.

Manual Actions and Lost Rankings

When a site's link profile contains a large volume of unnatural links, Google's spam team can apply a manual action, which is reported in Search Console. The affected pages, or even the whole site, then lose rankings until the profile is cleaned up and a reconsideration request is accepted.

Warning Signs in the Metrics

Metrics alone are not enough to judge a site, but some inconsistencies are very good clues. The idea is to cross-check several indicators rather than rely on a single score.

High Authority With No Traffic

A site displaying a Domain Rating or Domain Authority of 50 or more, but only a few dozen estimated organic visits a month, is suspicious. A genuinely authoritative site attracts traffic. This inconsistency is typical of reused expired domains, whose authority comes from old links unrelated to the current content.

An Unbalanced Trust Flow to Citation Flow Ratio

A high Citation Flow with a very low Trust Flow (a ratio below 0.3 or 0.4) indicates lots of low-quality links. Also check Topical Trust Flow: a cooking site whose main topical authority lies in gambling or cars probably has a problematic past, or present.

A Jagged Traffic Curve

Look at the organic traffic history over two or three years. A sudden drop coinciding with a Google spam or helpful content update, followed by stagnation, is a strong signal. So is traffic that depends on a few keywords unrelated to the site's stated topic.

Artificially Inflated Metrics

Third-party authority scores can be manipulated: a few links from high-rated domains, redirects from expired domains or large-scale link exchanges are enough to push up a score without Google attaching any value to it. If a site has gained twenty authority points in a few months with no news coverage, no traffic growth and no visible PR campaign, look at its recent referring domains: you will often find the explanation there.

Sudden Spikes in Referring Domains

Look at the curve of new referring domains over time. A healthy site gains links gradually, with occasional peaks when one of its articles gets picked up. A site that suddenly gains hundreds of referring domains in a single month, mostly from low-quality or foreign-language sites unrelated to its topic, is often the target of an artificial campaign designed to inflate its scores before it is put up for sale. That kind of spike is rarely followed by any growth in organic traffic, which is exactly the inconsistency to look for.

Warning Signs in the Content

A quick visit to the site often reveals more than any tool. Spend ten minutes browsing the latest posts and a few categories, reading them as an ordinary visitor would.

Topics With No Coherence at All

A site that publishes, on the same day, an article on mortgages, another on cat food and a third on online casinos has no editorial line: it is selling slots. A general-interest publication covers many subjects, but with a logical structure of sections and genuine news.

An Overwhelming Share of Sponsored Articles

If almost every recent article contains an outbound commercial link, often with an optimised anchor, the site exists to sell links. A healthy publisher mostly publishes its own content and accepts partnerships occasionally.

Fake Authors and No Identity

No About page, no legal information, no real way to get in touch, authors with stock photos and no presence anywhere else: these elements signal a site that does not stand behind its identity. Real publishers have a verifiable existence.

Signs of Mass-Generated Content

Articles that all follow the same template, with identical introductions, vague generalities, no concrete example, no figure and no sign of first-hand experience, are often produced automatically in bulk. Look for factual errors, outdated information presented as current and images that have nothing to do with the text. A site that publishes forty articles a week with a tiny team, or no visible team at all, is unlikely to be a genuine editorial project.

Warning Signs in Outbound Links and History

Analysing outbound links and the domain's history lets you confirm suspicions raised by the previous steps.

Outbound Links to High-Risk Industries

Use an SEO tool to list the domains the site links to. A heavy concentration of links to gambling, pharmaceuticals, payday loans or adult content, unrelated to the site's topic, is a classic marker of sites that sell links indiscriminately.

A Domain That Has Changed Its Life

Check web archives to see what the site looked like a few years ago. A domain that used to host a charity, a defunct business or an event, and now publishes a general blog, has very probably been bought for its authority. Also check registration and ownership change dates.

Shared Footprints Across Several Sites

Same theme, same menu structure, same authors, same contact address, cross-links between sites with no editorial reason: when several sites offered by the same seller share these traits, you are probably dealing with a network.

Sitewide and Footer Links

Lists of 'partner' links in the sidebar or footer, repeated on every page, are another warning sign, especially when they point to unrelated commercial sites. Google's link spam policies specifically mention widely distributed links in footers and templates. A publisher that sells this kind of placement is unlikely to be careful about the rest of its link profile.

The Ten-Point Checklist Before Buying a Link

Here is a list of quick checks to apply every time. If a site fails two or three of these points, move on to the next one. The SEO metrics guide on this blog explains how to read each indicator in detail.

The Numerical Checks

One: estimated organic traffic is consistent with the displayed authority. Two: the two-year traffic curve shows no unexplained sudden drop. Three: the Trust Flow to Citation Flow ratio is above roughly 0.5. Four: the main topic of the site's authority matches its content. Five: the number of referring domains grows steadily, with no abnormal spikes.

The Editorial Checks

Six: the editorial line is consistent and the site publishes its own content. Seven: sponsored articles remain a minority. Eight: outbound links do not point heavily to high-risk industries. Nine: the site has a verifiable identity (publisher, legal information, contact). Ten: the domain's history reveals no suspicious change of life.

What to Do If You Already Have Dubious Links

Discovering links from PBNs or link farms in your profile does not necessarily mean you need to act urgently.

Assess Before You Act

If these links are few and you have no manual action in Search Console, Google is most likely ignoring them. Focus on acquiring quality links. If you bought them, simply stop acquiring new links of that kind.

Clean Up After a Manual Action

If you have a manual action, ask the sites concerned to remove the links where possible, disavow the remaining domains with the disavow tool, then submit a reconsideration request explaining the steps you took. Document every step.

Choose an Intermediary That Vets Sites

The best protection is still to use a platform that checks sites before listing them. On LinkBooster.media, publishers who want to sell links go through a review of their site, and buyers can see the metrics and topic before ordering.

FAQ: PBNs and Toxic Backlinks

Answers to the most frequent questions about site networks and low-quality links.

Are All Expired Domains PBNs?

No. Taking over an expired domain to build a genuine editorial project in continuity with its former topic is legitimate. The problem arises when the domain is used only to exploit its past authority and sell links, which Google calls expired domain abuse.

Can a PBN Work Without Being Detected?

Some work for a while, but networks resold to many clients leave footprints. When a network is detected, all its links can be neutralised at once, and the investment is lost.

Should I Disavow Every Low-Quality Link?

No. Every site receives spontaneous low-quality links, which Google ignores. Disavowing is mainly justified after a manual action or when you have a large volume of artificial links that you solicited.

How Can I Tell Whether a Link Seller Is Trustworthy?

A trustworthy seller lets you check sites before buying, clearly states their topic, language and metrics, does not promise guaranteed results and does not offer massive bundles at rock-bottom prices.