IME most people will do what they can get away with. Most people who behave well only do so because they don't perceive that they could get away with behaving badly. I see this is especially working in customer service, where people know that the rule is "the customer is always right" and that we employees are unable to stand up for ourselves. The opportunity to get away with bad behavior presents itself, and suddenly a lot of "normal" "nice" people let their nasty side out. So what it essentially boils down to is that you have to set the rules. You have to decide what you will and will not tolerate, period. If you tolerate bad behavior, mind games, etc then there are going to be a lot of people who happily seize the opportunity.