[dang]

It's more complex than that. Sometimes people create throwaway accounts so they can share more information than they'd otherwise be able to, and really are experts or insiders on a topic. It's not always easy to tell such cases apart from fabricators or trolls, but it's important to try, and to give people the benefit of the doubt. I generally go by how substantive the comments are or seem (admittedly not an infallible test).