"I don't trust 'natural.' People are always dying of natural causes."-- Woman looking at food labels, in a Richard Guindon cartoon Roll playing games? Photo: Laura Cacho. Shoppers of the world, I have just one question: Are you an eco-chump? Lots of us try to shop green. We buy unbleached paper towels and recycled products, some with more than 5 percent post-consumer content. Commend McDonald's for banning Styrofoam, and shun them for lying about beef fat in the fries. Save our paychecks because we suffer from Prius envy. Wouldn't be caught dead at Wal-Mart because, well, it's Wal-Mart. But a …