Here is are two charts showing the distribution of customer tags on Amazon.com for Ann Coulter’s Godless: The Church of Liberalism. The first shows tags 1-25; the second all 881 tags.
The distribution is not too far from the classic “long tail” pattern common to social data. Although the common tags are common, fully 75% of the tags are used only once.
It’s an even better example of another characteristic of social data, that “user generated content” is all about context, not just object. LibraryThing members and Amazon customers are tagging the same book. But while, on LibraryThing, where you have to have a book to tag it, Godless has a fairly unremarkable tag cloud, touching on its subject matter and point of view, on Amazon, the tagging has devolved into a shouting match. I don’t think the people who tagged the book “asshat,” “vomit” or “w h o r e” are using tagging as a memory aid (“I forget—what books did I think are ‘asshat’ anyway?”). They’re using tagging as a sort of drive-by review.
Now, a case can be made that Amazon’s tags are signaling something important—this is a “controversial” book indeed! The LibraryThing tag cloud doesn’t show that as starkly. On balance, however, I think opinion tags corrupt the value of tagging.
Either way, I think this example demonstrates that tagging isn’t a simple matter of putting users in front of taggable stuff.