Advertisers always look at pagerank when purchasing text link ads. That's a given. And Savvy advertisers know to look at other statistics of a web page as well, like Google backlinks, age of domain, and Alexa rank.
But there is one important factor that is often overlooked, and it could be one of the most important factors of all.
Uniqueness of content, in my opinion, should be one of the strongest factors in determining the link value of any webpage.
Uniqueness of content provides a good, quick indication of how good the content is. Obviously, the better the content, the better chance it has of retaining it's traffic, pagerank, and overall advertising value.
While it's possible that a page can be unique, and still not be good content, unless you have the time to read every word of a page, there's just no other easy way to weed out the good from the bad.
You can check the uniqueness of a page using one of my favorite online tools, www.copyscape.com. Copyscpe will take a webpage you give it, and scour the internet looking for other webpages that have the same content on it.
This will keep you from advertising on sites that are completely syndicated. Syndicated sites often will quickly lose their high placement in SERPS and pagerank. Advertisers should keep in mind this risk when considering advertising on syndicated sites.
