It's very amusing and a reflection of our society..
People who buy these tshirts/bags/numerous other items of apparel with Che's image on it do so for what they believe is the 'coolness' factor. It doesn't matter that they either don't know about his history and who he was or understand they are wearing the image of a brutal and ruthless man who had no qualms murdering people who he believed betrayed him, it's cool man!
I swear our society is becoming dumber by the day...