Google has a new Webmaster Help video out talking about how it looks at quality of content that doesn't have many links pointing to it.
Specifically, Matt Cutts takes on the following question:
How does Google determine quality content if there aren't a lot of links to a post?
"In general, that sort of reverts back to the way search engines were before links," he says. "You're pretty much judging based on the text on the page. Google has a lot of stuff to sort of say OK, the first time we see a word on a page, count it a little bit more. The next time, a little more, but not a ton more. And that after a while, we say, 'You know what? We've seen this word. Maybe this page is about this topic,' but it doesn't really help you to keep repeating that keyword over and over and over again. In fact, at some point, we might view that as keyword stuffing, and then the page would actually do less well - not as well as just a moderate number of mentions of a particular piece of text."
He continues, "We do have other ways. In theory we could say, 'Well, does it sit on a domain that seems to be somewhat reputable? There are different ways you can try to assess the quality of content, but typically, if you go back to a user is typing possibly some really rare phrase, if there are no other pages on the web that have that particular phrase, even if there's not that any links, then that page can be returned because we think it might be relevant. It might be topical to what the user is looking for. It can be kind of tough, but at that point, we sort of have to fall back, and assess based on the quality of the content that's actually on the text - that's actually on the page."
A few years ago, after the Panda update was first launched, Google shared a list of questions one could ask themselves about their content to get an idea of how Google might view it in terms of quality. You might want to check that out if you haven't yet.
Image via YouTube