Charlie O’Shea previews Amazon (AMZN) earnings and discusses the high bar the Street has set. Amazon’s going to have to “hold the line on margins” on the retail side, which may be difficult because it tends to make its money from discounting, he argues. He’s incredibly interested in the results this quarter. He lays out spending expectations for AWS, as well as what’s riding on their advertising business. “The company’s incredibly opaque,” he adds.