Lots of people wear the t-shirt while knowing nothing about the man. Some actually know about him and still admire him or think that on balance, he was a romantic communist.
I've seen more of the former in the United States and more of the latter in the United Kingdom.
Both groups disgust me. As do people who sport the Soviet hammer & sickle--whether out of admiration of communism or for stylistic purposes. I cannot abide either the ignorance in most cases or the moral relativism in the rest.
While talking about the so-called Che t-shirt phenomenon with friend, Branden B., he directed my attention to a couple of posts at The Volokh Conspiracy by Ilya Somin. Check them out here:
Together, they effectively highlight Guevara's atrocities, his t-shirt wearing fans' ignorance, and his apologists' moral relativism/equivalence (& idiocy).
America is a free country and people have the right to sport whatever ridiculous garb they please. I also have a right to point out when they are useful idiots--"fronting" for a mass murderer.