Good graphs are extremely powerful tools for communicating quantitative data clearly and accurately. Unfortunately, many of the graphs we see today are poor graphs that confuse, mislead or deceive the reader. That often occurs because the graph designer is not familiar with principles of effective graphs or because the software used has a poor choice of default settings. We point out some of these mistakes including misusing color, deceiving the audience, using inappropriate designs and poor tables. In most cases, very simple changes make the resulting graphs easier for the reader to understand.