Spam score is the most misunderstood number in the marketplace table. Buyers treat it as a penalty flag, publishers treat it as an accusation, and both readings are wrong in ways that lead to bad decisions.
What the number actually is
Moz built spam score by taking a large sample of sites penalised or removed from search results, identifying characteristics they disproportionately shared, and then scoring every other domain by how many of those characteristics it exhibits.
So a spam score of 30% does not mean the site is 30% spam, and it does not mean Google has taken action. It means the domain shares a set of features with sites that were penalised. It is a correlation, expressed as a percentage.
This distinction matters because it explains the false positives. Perfectly legitimate sites sometimes score high because of superficial characteristics, and genuinely manipulative sites sometimes score low because they were built carefully.
The kinds of things it counts
Moz does not publish the full list, and it has changed over time, but the flags fall into recognisable groups:
- Link profile shape. Very low or very high ratios of followed links, thin linking-domain diversity, links concentrated from known low-quality neighbourhoods.
- Domain characteristics. Certain TLDs, very long domain names, keyword-stuffed domains.
- Site structure. Very few pages, missing contact information, no meaningful navigation.
- Content signals. Thin pages, heavy commercial anchor text pointing outward, large volumes of outbound links relative to content.
Notice how many are structural rather than editorial. This is why a small, legitimate, single-purpose site can score higher than expected.
Thresholds worth using
Treat these as triage rather than rules:
- 0–10%. Normal range for established sites. Do not think about it further; judge on other criteria.
- 10–30%. Worth investigating. Often explained by something benign, but you should find out what it is rather than assume.
- 30–50%. Strong caution. Buy only with a specific reason and after reading the site properly.
- Above 50%. Walk away. Whatever the explanation, the risk is not worth a placement.
How to investigate a moderate score
When a site you otherwise like scores between 10% and 30%, three checks usually explain it:
- Look at the topic spread. Open the archive. A site publishing on casinos, insurance, CBD and software in the same month is a link inventory, not a publication. That is the score being right.
- Check the outbound link density. Count external commercial links in a few recent posts. Five or more per post on a short article means the site exists to place links.
- Check the site's own basics. Is there an about page, a named team, a contact route, a privacy policy? Their absence is both a spam flag and a practical problem, because you will need to reach someone if a link breaks.
If all three come back clean, a moderate score is usually structural noise and the site is fine.
The combination that should always stop you
Individually, most signals are ambiguous. In combination they are not. Walk away when you see:
- High authority, high spam score and negligible traffic together. This is the classic built-profile signature.
- A high spam score alongside an unusually low price for the authority band. Cheap access to a strong domain has a reason.
- A high spam score on a site that only accepts sponsored content. There is no audience to protect, so nothing constrains the behaviour.
For publishers: bringing a score down
If your own site scores higher than you would like, the fixable causes are mostly structural: publish a real about page and contact route, narrow your topic range, cut outbound commercial links in older posts, and stop accepting placements from unrelated niches. Scores respond slowly, over months rather than weeks, because they follow the underlying characteristics rather than the intent.
Where to see it
Spam score appears on every listing in the marketplace table and on each media profile alongside the date Moz last returned it, together with linking domains, followed referring-domain share and equity links, so you can read the score in the context of the link profile that produced it.