There are many ways that graphs can be misleading. Depending on how you set up your graph, the same set of data can look very different. It's important to understand that there are some common mistakes to avoid when making graphs. In addition, advertisers have been known to intentionally make their graphs misleading to make their data match their point.
In the image provided, this is a good example of a misleading graph.
First, notice that we know that the first bar is 10 and the second bar is 50. However, there are no labels on the horizontal or vertical axis so we don't know what the bars represent.
In addition, notice that there is no title on this graph. Since there is no title on the graph, we don't know anything about the data.
Further, look at the scale on the vertical axis. Notice that it's an uneven scale. The uneven scale makes it appear that the first bar is closer to the second bar than it actually is.
We could correct this graph by adding labels to the x and y-axis, adding a title to the graph, and making the scale on the vertical axis even.
Another way graphs can be misleading is using the wrong type to represent data. For example, a scatter plot might be better than a regular graph in some cases.
Lastly, graphs can be misleading by adding a wide range of numbers to show and increase or decrease relatively small to how it actually is.