An anonymous reader writes: The used smartphone market is thriving, with many people selling their old devices on eBay or craigslist when it's time to upgrade. Unfortunately, it seems most people are really bad at wiping their phone of personal data before passing it on to a stranger. Antivirus company Avast bought 20 used Android phones off eBay, and used some basic data recovery software to reconstruct deleted files. From just those 20 phones, they pulled over 40,000 photographs, including 1,500 family pictures of children and over a thousand more.. personal pictures. They also recovered hundreds of emails and text messages, over a thousand Google searches, a completed loan application, and identity information for four of the previous owners. Only one of the phones had security software installed on it, but that phone turned out to provide the most information of all: "Hackers at Avast were able to identify the previous owner, access his Facebook page, plot his previous whereabouts through GPS coordinates, and find the names and numbers of more than a dozen of his closest contacts. What’s more, the company discovered a lot about this guy’s penchant for kink and a completed copy of a Sexual Harassment course — hopefully a preventative measure."