I don't know if you missed the "assisted suicide" discussion the last few years, but consent doesnt make illegal legal. But in the case of prostitution, no law would be broken by the act itself, only the law that prostitution is just illegal.See that is a problem consent can't be the only thing that prevents someone from buying something from another person. If you consent to me purchasing the mutilation of your body is that okay? you gave me consent? What about me mutilating your childs body if all we need is parental consent? You can't base something as okay or legal on the sole fact that some individual might give 'consent'.