The stern photo of revolutionary Che Guevara taken by Alberto Korda in 1960 is one of the most reproduced images on the planet, appearing on posters, flags, postcards, T-shirts, and even bikinis. Sadly, the ubiquitous appearances of Che — hailed today usually by his first name only — demonstrate the near-total failure to educate people about the blood-soaked cruelty he really represented. But there are, thankfully, some limits to the use of Che’s famous image — if people complain. A recent e-mail sent by the Environmental Protection Agency to mark Hispanic Heritage Month included Korda’s image of Che along with...