How Does Google Find Low Quality Backlinks?
Easy. You tell Google every time you check if your backlinks are indexed.
A huge problem for SEOs is building backlinks, checking if they are indexed, then moving on without tipping off Google. Lately, there’s been a huge push for Google to detect and discount these backlinks from their index.
The most common way to check if a page is indexed is to use the “info:” or “site:” operator in Google. This little known search trick is almost never used by the general public and is almost always used by SEO tools to check if a page is indexed. A query using the “info:” operator looks like this:
Since it’s pretty much only SEO tools that use this Google feature, it makes sense that Google would just check their logs for all the URLs following the “info:” operator and assume those were low-quality backlinks. In essence, every time you check if a page is indexed, you tell Google where you put that backlink.