The BBC actually exchanged messages with some of them. People on Facebook in particular use real names and have profiles on other websites, including places where they and their family work and can be contacted using real contact details. And there's some extent of life history faking that bot creators aren't going to go to just to be one of dozens of people posting 'Good job Boris' a decade after the account's first formed.

Obviously it's more difficult on Twitter when accounts tend to be anonymous, connections are one-way, a lot of activity is retweeting and very little of it is personal photos, and many real accounts have been around for a lot less time.