I've been taught that with any visualization, make sure it doesn't:
A. Don’t show much data. B. Show the data inaccurately. C. Obfuscate the data.
Even things that are obviously not done maliciously can mislead people, such as putting categories in a bar graph in alphabetical order rather than from most to least.
Although this is something that the industry doesn't really care if you know or not, it will help in correctly identifying patterns from visualizations