The internet, and in particular this site, thrives on anonymity. While many of the users here feel confident enough in the community to use their real name (and it does have real world implications, for better and worse), there is no binding requirement for real names.
And it's fine when the user names are clearly fake. Clearly a user name like Potato or "user $n$" is not a real name. It's also fine when the user name is some real world derivative of the person's name, e.g. robjohn.
But sometimes people use names which can be seen as real names. I can never know if a user called John Bedsmith is an actual person, and if searching online shows that this is a real person then I have no way of knowing if that is truly the person behind the username. That's disturbing and somewhat less fine, but still generally acceptable.
But what about names of celebrities and political figures? User names like Fidel Castro, Justin Bieber, Adolf Hitler and more. All featured here. Some time ago there was a user who decided to circumvent this by changing one obvious letter, and opened a handful of these accounts. Often with a gravatar photo of the persona after which the account was named.
So I wanted to bring this up to discussion. How permissive should we be when the account has a name which is obviously a real world person who is very unlikely to participate here? Even more when the site is used to make jokes like that (e.g. Obama asking a question and Bush answering, often without an actual mathematical content in the answer)?
Should there be some line in the sand, and if not a line, at least some open neighborhood in the sand?