I'll disagree about one particular point here:
"Sex has values and judgments attached to it that eating, for example, doesn't"
Not in any world I've lived in. The choices people make about the food they eat IS frequently judged and valued. The term "fat slob" comes to mind first here, as it's a value judgment about a whole person made from looking at one particular aspect of their behavior - their eating habits. Eating habits are frequently "disgusting" or "tidy", and people's choices of meals are "wholesome" or even "revolting". All of these terms are my attempt to illustrate one important thing: everything about you gets judged. I don't mean this in any religious sense either, it is a simple fact of life though that those around you judge your character constantly and through every action you take (or don't take).
In fact, I bet that if people were truly honest about how often you make value judgments on a person based on a small sample of their behavior (clothes, food, manner of speech, etc), we wouldn't have any room to talk about anything else.