That quote is attributed to one of the most evil men who ever lived, Dr. Joseph Goebbels, propaganda minister of the Third Reich. Unfortunately there is more truth in that statement than we would like there to be. Goebbels used that principle to run his black propaganda campaign against Jews and he succeeded in the most horrific way imaginable.
Today that method is still used to carry out "character assassination" of people and groups who the attacker doesn't like or sees as a threat. Unfortunately the main-stream media could be viewed as parrots who happily repeat whatever they hear without any thought of determining the truth or accuracy of what they so obligingly repeat. This means that a character assassin has an easy time of it in this society.
So next time you see something reported about a person or group, think twice before you accept it as fact. And, if you are feeling curious, do some research into the person or group being attacked and you will probably find that they have stood up against a vested interest and cost that vested interest a barrel load of money. At that point you can take the bad stuff you heard and throw it where it belongs - in the garbage.