What should parents never do in front of their children?

I think parents should not swear in front of their kids. They also should refrain from engaging in behavior that is harmful to others, even if it's only verbal. I also think parents should not be dishonest to others. But it's also important to remember that even the little things can send the wrong message. Passing off acts of omission as "white lies", for instance, can establish a harmful behavioral pattern which can evolve into more dangerous acts such as cheating, or lying to parents because they might think it can be justified as simply "white lies".