But what I found is that universally people who talk about sustainability make decisions that are worse or orthogonal to the issue...
Sorry, but I'm calling bullshit. I agree that there's a lot of inconsistent posing that goes on around these issues, and it frustrates the hell out of me too. But claiming it's universal is just inaccurate. (At best it's a sloppy exaggeration.)
There are vegetarians whose primary or only concern is sustainability, and who try to make food choices that reflect this. I know some of them personally.
To infer that anyone who makes decisions that don't exactly mesh with "reasonable science-based consequentialist GHG/sustainability concerns" are "just pretend[ing] to be concerned about GHG and sustainability" is unjustified. As I've noted elsewhere, there are a often tensions between the various rationales for restricted diets. Which means that if you buy into more than one of these rationales, you'll sometimes end up having to make awkward compromises between them. That doesn't mean that you don't really care about any of them; it just means that the world isn't conveniently designed to let you have everything you want.
I have noticed that among philosophers, vegetarianism of one form or another is quite common. In fact, I became a vegetarian (technically a pescetarian) myself partly out of respect for an undergraduate philosophy professor. I am interested in finding out if there is a similar disproportion in the Less Wrong community.
I didn't request that this go into Yvain's survey because I want more information than just what animal products you do or don't eat; I'd also like to see nuances of the reasons behind your diet. There are a lot more shades than carnivore/vegetarian/vegan - if you want to be a vegetarian but are allergic to soy and gluten, that's a compelling reason to diversify protein sources, for instance. I'd also like to hear about if you avoid any plant foods (if you think they're farmed in a way that's environmentally destructive or that hurts people or if you have warm fuzzy feelings for plants, maybe). Here are some questions that come to mind: