It is widely believed that medically inert treatments ("placebos") can bring about therapeutic benefits. There is also evidence that medically active treatments may also have "placebo" effects. Since anything that has the potential to benefit patients ought to be exploited, subject to appropriate ethical standards, it has been suggested that more should be done to investigate and exploit the power of the placebo for therapeutic benefit. I explore the acute epistemic and ethical constraints that such exploitation is likely to face, and conclude that effective exploitation is unlikely.