But books aren't commodity goods, like tobacco. When a blogger recommends a book (or a list of them) he's recommending specific books to read, usually on a nar

But books aren't commodity goods, like tobacco. When a blogger recommends a book (or a list of them) he's recommending specific books to read, usually on a narrow topic that his audience is interested. His interest lies in recommending books that his audience will enjoy (or learn from, in this case), so that they trust his recommendations in the future.