What are some common characteristics of websites that are part of a PBN?

There are a number of common red flags and footprints that can indicate a website is likely part of a private blog network (PBN). A few signs to look out for are:

First, the sites usually have extremely thin, low-quality content that exists solely to host outbound links. We're talking spun garbage content, heavy keyword stuffing, that sort of thing. The content has no real value beyond link placement.

Speaking of the links, PBN sites tend to link out with commercial, money-keyword-rich anchor text at an unnatural ratio compared to how real sites link. You'll also often see wildly different, unrelated sites all linking to each other, which is really fishy.

The domain names themselves are another hint - many PBNs use nonsense, randomized domain names to avoid appearing as a connected network. Short, brandable domains on PBNs are rare.

Digging into the technical side, you'll frequently find PBN sites reusing the same hosting providers, name servers, WordPress themes/plugins, and other services that leave a detectable footprint if you know what to look for.

Whois details are usually kept private too to hide ownership connections across the PBN domains. And the sites strictly monetize by selling private links rather than displaying ads or offering products/services like a real site would.

So in essence, PBN sites just scream "fake!" through their thin content, super aggressive link practices, technical fingerprints, and lack of any business model beyond paid links. But that's because they exist solely as link homes, not legitimate web properties.

Of course, PBN operators try to hide these footprints as much as possible. However, an experienced eye can usually identify a PBN site based on hitting several of those common red flags. Avoid them - they're still a violation of Google's guidelines!