Philosophers seem to delight in the idea that the common good is hard to define. I'm an economist. I don't see much wiggle room. The wiggle room that exists is:

(1) How much do you care about whom? In particular, do you care equally about everyone, or are you a jerk?

(2) How do you weight the relative value of things like money, health, longevity, entertainment?

(3) At what rate does the marginal utility of such things diminish?

Okay maybe that's a lot of wiggle room. Still, under any reasonable set of weights, making millions of people sick is not worth the money 3M made.