When it comes to link building, quality is what matters most. I don’t buy the “any link is a good link” notion. Your time is limited and the last thing you want is wasting it to get useless backlinks.
Social bookmarks if used incorrectly are ones of those kinds of links that border with useless. What good is a link from a page with potentially 100s of outgoing links or from a page buried deep deep down the hierarchy of the site? Your time is better spent getting quality links than spamming social bookmarking sites.
