Generating Facebook accounts in bulk is not easy.  I&#x27;m not suggesting that it&#x27;s a panacea, but if you&#x27;re looking for something to indicate a real purchase this would be strong.  If someone logs in with Facebook and has 10+ friends then I&#x27;m going to say they are 99% legit.  Plus you can look at their profile manually if you&#x27;re in doubt.  Of course you also offer email but those orders get more scrutiny.  HN is an echo-chamber of hate for Facebook login but the real world (and I suspect your target market) does not share this.