Why do conservative bloggers ALWAYS assume that I'm a liberal?

Because most Americans have no idea what a libertarian really is. They think political ideology has to be divided into one of two camps. Conservatives brand you as a liberal because you probably hold liberal views towards social issues like homosexuality and religion. Liberals brand you as a conservative because you most likely hold conservative (or classically liberal) views towards economics. It's just something you're going to have to get used to. I cant say that from personal experience since I tend to regard myself as a social democrat but I can understand the frustration you might feel from being lumped into one of two categories, neither of which you completely identify with. My father for example displays all the attitudes of political libertarianism despite the fact that he is not willing to recognize it. He identifies himself as a republican despite the fact that he disagrees with the republicans on most social policies. He even acts insulted when I insinuate that he is in fact a libertarian. Go figure.