You don’t have to be one of Google’s accountants to know that in the digital world — advertising is where the money’s at. So for years, companies have been making cash with fraudulent advertising. Think one of those banners you see on a website or a page of search results that touts the latest fat-zapping pill. It wasn’t bought and sold through the normal routes. Sometimes these ads can actually infect your computer with malware. And the latest place to find them is on YouTube. Emily Steel is a reporter for the Financial Times, and she’s been covering the story.