Originally Posted by mjtaylor
You may be right; that relevance of a link is not proven
as a ranking factor, but I would wager money it has weight. In any case, if it isn't a factor now, we can be sure it will be. See: Google's Reasonable Surfer: How the Value of a Link May Differ Based upon Link and Document Features and User Data
And whether it's a ranking factor or not, it's a usability factor of the highest order, and that means it highly impacts the quality and quantity of *traffic*
and conversions you will get from a link.
It is important, when speaking of the "relevance of a link," of make a distinction between a links role in PageRank vs ones Link Profile.
For the former, "relevance" is irrelevant; for the latter, it may
be quite important.
Moreover, it must be understood that determining the "relevance" of is no mean feat," that that which a human sees a being relevant, such as links to resources that complement the source, may bear a relationship that is undetectable to an SE's indexing engine.