There are habits and activities that leave people open to manipulation. I'm not saying they are wrong or right, just pointing out that these behaviors make you open to being manipulated... Here are a few general categories of behaviors that manipulators seek out:
Believing something because you heard someone say it on a news show on cable TV.
Being a child (or acting like one).
Buying penny stocks.
Repeating a mantra heard from a figurehead or leader of a tribe without considering whether it's true.
Trying to find a short cut to lose weight, make money or achieve some other long-term goal.
Ignoring the scientific method and embracing unexamined traditional methods instead.
Focusing on (and believing) easily gamed bestseller lists or crowds.
Inability to tolerate fear and uncertainty.
Focus on now at the expense of the long term.
Allowing the clothes of the messenger (a uniform, a suit and tie, a hat) to influence your perception of the information he delivers (add gender, fame, age and race to this too).
Reliance on repetition and frequency to decide what's true.
Desire to stick with previously made decisions because cognitive dissonance is strong.
Inability to ignore sunk costs.
Problem saying 'no' in social situations.
Add this to the mix of ideas to understand why the Doom-and-Gloom message is so effective.