Cookie stuffing is an unethical way to earn lots of money from Affiliate advertisers. A user clicks a Search Engine listing for (say) a supposed political Web site. But the site that the search engine spider saw is not what the surfer will see. Instead of getting information about Sarah Palin or Joe Biden, the page clicks on an affiliate firm's advertisement, and shows (for example) a page for purchasing a book about Joe Biden or Sarah Palin. The firm boasts that it brought nearly $9000 in affiliate revenue to a site that got 1,000 visitors a day. And - these are cautious folk who only send 10% of the visitors to the affiliate Web site. A comfortable way to make a living - for Google too.
If Webmasters are not supposed to use Black Hat optimization tricks, should Google be making a living by advertising Black Hat software?