The worst thing is that nobody knows what it means. As Isaac points out, all food is made of organic compounds, as it's all carbon-based. So obviously that's not what's meant. Originally it seemed to mean not genetically modified – this was back when loads of people were banging on about how we shouldn't "play God" with our food. Then it somehow turned into no chemical pesticides. And what if stuff is artificially bulked up by injecting it with water? I assume there must be rules about this kind of thing, but I don't believe there's any public awareness of them. I can't even find a definition on the website of DEFRA, which certifies organic food in the UK.

I honestly think a lot of people who buy organic do so because they think it's more moral in some undefined way, or even just that if it's more expensive it must be better. For all I know there may well be benefits to organic food*, but if so, nobody's told me what they are in a way that makes sense.

*By which I mean food that is labelled as organic in supermarkets, as opposed to any individual's opinion about what constitutes "real" organic food.