A comment at Overcoming Bias reminds me that things are exactly the opposite in meta-ethics. This is the discipline that studies what we mean when we say something is right or wrong, whether there is any truth to such judgments and, if so, whether we can ever know what that truth is. Pope Benedict thinks it matters what your answers to these questions might be. Dostoevsky thought it mattered. Alfred Hitchcock's Rope is about a murder inspired by moral noncognitivism.
Metaethicists, on the other hand, will without exception tell you that it doesn't matter. Noncognitivists, error theorists and skeptics can all oppose torture and donate to Oxfam. Nothing turns on what they do for a living. As the comment says:
Most meta-ethicists tend to be rather impatient with people who think that if objectivism is false then everything is permitted, or morality is undermined, or relativism is true, and so forth. None of these things follow. Nor do any substantive consequences for the major disputes within normative ethics -- e.g. that between consequentialists and Kantians. The fact that someone is an expressivist or subjectivist or naturalist or fictionalist doesn't tell you anything about their substantive views.
But should we non-experts trust them on this? After all, they can't agree about whether morality consists of feelings or judgments -- how come they agree on this? Don't they have an interest in persuading the taxpaying student-spawning public to believe Hitchcock and Dostoevsky wrong? You're going to trust a self-proclaimed moral fictionalist to tell you the truth about the negative externalities associated with his industry?