> Everyone I've ever known says something like "you don't talk much, do you" or something equally obvious. I used to wonder if people ask others the obvious "you're fat, aren't you" etc.

Well if someone is fat I don't have to wonder if they're fat, because I annoy them and missed their hints to get lost, or whether they just lost a loved one and are not in the right mood, or because they're a 'strange' creature.