Yahoo's organic search results aren't always organic. I don't think the average Yahoo user has any idea that many Yahoo search results are paid listings via Yahoo's paid inclusion product, Search Submit Pro. It's sort of like buying organic apples and finding out some of them were sprayed with pesticide.
Yet, I can see my way past the ethical minefield paid inclusion presents. There is no expressed contract that states that the organic search results are 100% organic. That's an assumption that many users make and which Yahoo simply fails to correct. There's no 100% organic 'sticker' on the Yahoo search results.
The real question for me is how paid inclusion impacts search engine optimization (SEO). "Why do I get only 5% of my organic traffic from Yahoo when they're 20% of the search market?" This is a common refrain I hear from a rising tide of companies. There are a number of possible explanations for this discrepancy.
Sites optimize for Google and not Yahoo
Google is the force in search with a 63% market share in August 2008. For that reason, sites optimize for Google first and Yahoo a distant second. The algorithm for each is different with Google placing far more weight on off page factors like links.
In particular Google seems to have a better quality link algorithm that helps place sites in appropriate neighborhoods of knowledge. Yahoo certainly looks at links but it seems tied to link popularity and link ratio. This means you have to overwhelm Yahoo with inbound links to really have an impact.
Result: Google optimization might not help you with Yahoo.
Yahoo's index is slow to update
There's no question that the Yahoo index is slow to update and is less agile than Google's index. What Google indexes and categorizes in hours could take Yahoo weeks or months. It's not that it doesn't get into Yahoo's index, it's that Yahoo doesn't categorize it so that it can be served to users for relevant searches. In many ways it might as well not exist.
Google is also constantly tweaking the search algorithm. If you're working in SEO you're accustomed to the changing nature of the Google algorithm. However, It's unclear how often Yahoo changes its algorithm, but it's far less than Google and it's not nearly as big a deal when they do. The Yahoo search index has calcified.
Result: It could take a long time for your efforts to pay off on Yahoo.
Paid Inclusion takes up search engine result shelf space
While there are no guarantees that paid inclusion will get you top results, it certainly takes up shelf space on search results. As more companies use paid inclusion, the number of organic search results goes down, making it more and more difficult to optimize vital keywords.
It seems logical that Yahoo, particularly in its current financial situation, would want to increase the number of paid inclusion results. As a cost per click product it would mean a greater probability of generating revenue with every search engine result page.
What's the keyword coverage for paid inclusion? What's the average number of paid inclusion listings to organic listings? These paid inclusion statistics aren't available, so it's difficult to understand the real effect of paid inclusion. Instead we can only deduce from watching our SEO efforts and tracking organic search volume.
Result: Paid inclusion might not be the culprit, but it introduces another variable that defies tracking, thus obscuring all other SEO efforts.