Was that naked selfie you took really deleted before you sold your phone on eBay? A new study from security software vendor Avast calls into question the effectiveness of Android’s factory reset option, which many people have relied upon to delete personal data from their old smartphones before reselling or making a charitable donation with the old device. Avast — known for its security software on Windows, Mac, and Android — purchased 20 Android smartphones from eBay, which has around 80,000 used smartphones for sale at any given time. Among the data that Avast employees recovered from the phones were more than 40,000 photos — including 250 nude male selfies — 750 emails and text messages, 250 contacts, the identities of four phones’ previous owners, and one completed loan application.