I used to use Yahoo a lot, and now go there only for news and email - not for search, and will probably switch over for those old legacy uses as soon as I find something else.
In Firefox, if I go to the Yahoo search page, it would tell me:
Use Yahoo! to search from Firefox
which is something I am never going to do - for a long time now, Yahoo search results have always excluded mention of any aczoom.com link, other than somewhere way below in the search results. Given this, no way am I going to switch my Firefox search box to Yahoo - Google is much better.
This is why I presume there are so many pages on the web related to "SEO" - trying to figure out what search engines do, and how - it is too complex. For example - how come a search engine can list 100s of pages that all link-back or refer to the main page on a topic, but never have that main page show up higher on the search results?
aczoom.com uses Drupal and I suspect this issue is related to that, and URL re-writing is confusing the Yahoo bots. But there are also static pages at this site, and Yahoo does not show them either. And both Google as well as Microsoft MSN search get it right - for all Drupal hosted pages here, as well as the static pages.
So, Yahoo shall remain unused in the Firefox browsers that I use. Hopefully, this should have Yahoo engineers all concerned and rush to fix their search engine :-)!!! Until then, I'll stick with Google Search.
Older blog entry related to same topic: search engine fun