Money vs. Morals

It is obvious that consumers are responsible for their own decisions. What isn't obvious is the level of responsibility companies have to their consumers. Should companies sole focus be profit, at any "cost" to their consumers? What moral and ethical obligations do they have to their customers? For example, although they CAN (legally), SHOULD (ethically) cigarette or even fast food corporations sell a product that can be detrimental to the health of their consumers?