[rtpg]

Right, totally see what you're saying. In the junk food example (assuming fast food a la McDs...) it feels fairly noncontroversial to say there's health costs. Just then you get into convenience discussions (or even just enjoyment discussions) and now you're weighing health vs convenience and these are totally not fungible quantities. So you're already veering into subjectivity if you're saying "on balance it's bad".

There has to be a point at which you pull in preferences. But at least then you can split the "objective" from the subjective, and think about the details in earnest. Even when conclusions differ.