Anyone who’s engaged in link building for SEO in the past few years can tell you the biggest—and most important—concern of the strategy: getting penalized for posting spammy links. The era of quantity-based link evaluation has gone away completely thanks to revisions of Google’s Penguin update. The search engine giant can now tell easily whether your link is built “naturally,” with the intention to increase value to web users, or “unnaturally,” with the sole intention of increasing your rank.
Up until this point, determining whether your link is “natural” or “unnatural” has been grounded in solid evidence, but it’s mostly come down to a guessing game. If you choose a reputable source and post a link you genuinely think is helpful to the conversation, then in theory, it should be considered a high-quality link. Still, it’s easy to doubt yourself and worry about whether or not Google is picking up on your link building attempts and considering them to be unnatural.
Fortunately, Moz just released a new tool that might help put an end to those speculative worries. Operating under the Open Site Explorer tool you’ve probably used to map out your backlink profile in the past, the new “Spam Score” is designed to objectively measure how natural or unnatural your link appears.
How the System Works
After a few thorough rounds of research, Moz data scientist Dr. Matt Peters eventually boiled down the deterministic qualities of an unnatural link to 17 factors, which he called “spam flags.” The more of these spam flags a link has, the more likely it is to be penalized and the less authority it’s going to pass.
Spam Score, the name for Moz’s objective measurement, is a calculation of how many spam flags a subdomain shows. At this time, it does not function at a page level, nor does it function at an overall root domain level, but this shouldn’t stop you from gaining some key insights into whether or not your link has been posted on a high-quality site. You can find the Spam Analysis tab under Open Site Explorer—right now, it’s only available for subscribers, but you can sign up for a free trail to access the feature or wait until Moz inevitably rolls out the feature for free to all users.
Once you’ve selected a specific subdomain, the system will evaluate it based on those 17 spam flags, and tell you how many of those spam flags it is demonstrating. Between zero and four flags means the site is low risk, between five and seven flags means it is a medium risk, and eight or more flags means it is a high risk. The 17 flags are as follows:
Low MozTrust or MozRank Score—this is a calculation of overall domain authority.
Low site link diversity—this means the types of links pointing out isn’t diversified and seems unnatural.
Abnormal ratio of followed to nofollowed domains—high or low ratios make Google suspicious.
Low-quality content—if the content is thin or low-quality, it signifies a low-quality site.
Excessive external links—too many links pointing out mean it could qualify as a link directory.
High ratios of anchor text—improper anchor text use triggers a red flag.
Lack of contact information—without a phone number, address, or email address, the site could register as spammy.
Top level domain is associated with spam—if a subdomain is linked to a low-quality TLD, the subdomain becomes low quality by extension.
Numeral-containing subdomain—numerals are a bad idea for inclusion in a URL.
Few inbound links—if the site is large but contains few inbound links, its authority is weakened.
Abnormal ratio of followed to nofollowedsubdomains. The rule about domains applies to subdomains as well.
Few branded links. A lack of branded anchor text in inbound links triggers a red flag.
Few internal links. Without internal links, the quality of a site comes into question.
External links in main navigation. Hosting external links in a main navigation or sidebar makes a site appear less authoritative.
Few pages. The number of pages on a subdomain plays into how authoritative it is.
Excessive length. If a subdomain’s length is higher than average, it appears as a red flag.
Even if you don’t use Moz’s automated tool, you can use these 17 spam factors to evaluate whether you should post links on a particular domain.
Other Factors for Consideration
Remember, this tool is designed only to determine how spammy a given subdomain is. There are other factors you’ll need to consider when performing your ongoing link building. For example, even if a subdomain has zero red flags, it could be dangerous to use it as a link building opportunity if it has nothing to do with your line of business. And if you post an inappropriate link to the conversation, you could ruin your chances at gaining authority from the encounter.
Link building is still an evolving art, and you’ll have to pay close attention to the effects of your strategy if you want to improve over time. However, this new tool and the spam flags Moz uncovered should be very useful in helping marketers understand which subdomains are most valuable and which ones should be avoided at all costs.
Timothy Carter is the CRO for AudienceBloom. Since 1997 he's been helping businesses maximize their sales revenue from websites via content marketing, SEO and Internet Marketing strategies. Over the years he's written for publications like Marketing Land, Search Engine Journal, MarketingProfs and other highly respected online publications.