Are there any collections or blogs of bad data visualizations? I know I've seen such misleading graphics in the news or in print, made misleading either maliciously or thoughtlessly, but I usually see these as one-offs on social media. Has anyone started a collection of these to use as examples in their math/stats classes?
Check out the book Spurious Correlations by Tyler Vigen.
Are you interested in resources in languages other than English? Bad data visualization has no nationality.
There's a blog SmarterPoland.pl (in Polish) devoted to good and bad data visualization. It runs an annual (anti-)competition for the worst data chart. Here is the 2021 edition, along with the links to previous editions. It doesn't take (almost) any knowledge of Polish to understand how bad these charts are.