A WebmasterWorld thread has some interesting and almost unbelievable conversations of Webmasters stating that Yahoo! cares less today about the visible content on the page then it ever did before. Here are some quotes:
The suggestion put out there.
More recently i noticed that Yahoo will rank a page for a search string providing either a) the sites address contains the keyword or b) the page contains the keywords but only with VERY low density.
Someone else posts supporting data:
In April, I did a KW density comparison on the top 10 sites and found a pattern ranging from the #1 site (approx 3.9%) to lower KW densities. After May, there was NO pattern, so you may be correct
A humorous but supporting example:
One of my sites on a US server (not my own server, I hasten to add) was hacked a few days ago and the index page was replaced by a political extremist. Before I could put it right this site was spidered by Y! and now ranks on the first page for an important keyphrase, despite containing just a mindless rant, whereas before the hack it was nowhere.
I was about to shake this topic off and not cover it, but who am I to say. Figured it was worth a mention and a deeper look by some.
Forum discussion at WebmasterWorld.