In the recent Webmaster Help video, Google’s head of Search Spam, Matt Cutts, explains how Google determines a page has quality content if there are not many links to it. The question posed was:
“How does Google determine quality content if there aren’t a lot of links to a post?”
Matt says, this takes you back to the way search engines worked before links were used as a ranking factor. In such instances, Google judges the page on the basis of the text on the page. The first word seen on a page would be counted more, compared to the other words on the page. The second time a word is seen it would be counted “a little more, but not a ton more.” The more often the word is seen on the page, it becomes easier for Google to determine the page is about a particular topic. However, it doesn't help to keep repeating a keyword, because after a while Google starts to see it as keyword stuffing and this adversely affects the PageRank.
Google also sees to it whether the page is sitting on a reputable domain or not, to determine the quality of a page without enough links.
According to Matt, if a user types in a phrase for a query for which there are very few results, then Google might return a page even if there are not many links pointing to the page.Matt Cutts Explains How Google Determines the Quality of a Page without Many Links to it!,