While charts can be useful in showing data and relationships among data, they need to be as accurate, logical and graphically imaginative as possible.
Ben Greenman has an "I Love Charts" blog that reminds us that the very best charts are those that are totally defensible based on the facts. Here is one from Greenman's blog that is, I believe, wholly tautalogical:
And my favorite:
( Hat tip to Megan McArdle at The Atlantic.)