Bad Data

Bad Data is a site providing real-world examples of how not to prepare or provide data. It showcases the poorly structured, the mis-formatted, or the just plain ugly. Its primary purpose is to educate – though there may also be some aspect of entertainment.
As a side-product it also provides a source of good practice material for budding data wranglers (the repo in fact began as a place to keep practice data for Data Explorer).
New examples wanted and welcome – submit them here »