Reality shows contain wannabes who will do anything to get some TV time. Usually, the villains on most reality shows are most popular.
Some of these contestants might actually be obnoxious, but their behavior is also determined by what sells. So, you can't make a conclusion just based on reality shows.
In general, Americans are quite direct and straightforward in their speech at the cost of politeness. It is better to tell it to people's face rather than talk behind their back.