Many of the subjects were difficult or impossible to relocate, so a large part of each chapter is usually him tracking them down and talking to related characters. Sadly, he's not as interesting as his subjects. And even his subjects (those he can find) turn out to be not as interesting as his subjects. I think he was hoping to make some sort of connection with these people. With the cameras off, just hanging out, he wanted to maybe get deeper under the skin of the subjects, really find out what made them tick as people. He doesn't really find what he's looking for, and his disappointment comes through in his writing, making the book strangely sad. Still plenty of weird, but as an aficianado of weird... it was kinda tame.
Perhaps the wisest observation comes from Theroux's epilogue, quoting Speed Seduction guru Ross Jeffries: "Have you ever argued with a member of the Flat Earth Society? It's completely futile, because fundamentally they don't care if something is true or false. To them, the measure of truth is how important it makes them feel. If telling the truth makes them feel important, then it's true. If telling the truth makes them feel ashamed and small, then it's false."