>That is an argument for voluntarily joining the most despicable of organisations with the goal of fixing them from the inside.
More 'damage control' than 'fixing them', but sure, close enough. The point is, do not compare 'this job is evil, I produce -10 units of global utility' and then 'this job is good, I produce +20 units of global utility' looking only at your output. Instead, compare 'By taking this job, I will produce -10 units of global utility, instead of someone else producing -50', in which case the gain from you taking the job is +40.