From the article, I think There’s a lot of unexpected trouble that we (a flight attendant) can not control (some trouble) occurred in flight.
For example,the top three annoying behaviors involve the invasion of personal space: sitting in a seat that’s being kicked, smelling a fellow passenger’s body odor, and sitting behind someone who reclines the seat too far. So there’s no way to escape these annoyances when you’re 30,000 feet in the air. Overall there are an annoying behaviors to make a passengers get an unsatisfied experience.