As a freelancer there is always a mercenary element. I will take the next appropriate role to ensure that the bills are paid and that there is food on the table (not sure it is fair to say that living in a first world country).
I do avoid certain project types; offensive military software, nuclear power station control software, pornography. It isn't that I disapprove of these applications, per se, it is just that I don't want the responsibility. It is a similar feeling to how I feel about the armed services personnel, police officers, etc. I don't want to do it but I am glad that there are those that do.
I always try my best to ensure that, not only myself but the whole team produce the best results possible given the situation we find ourselves in through best practices, techniques and appropriate use of software available.
Would I prefer a project that assisted those in some altruistic endeavour such as searching for the cure to cancer, running a soup kitchen, getting fresh water supplies for those in countries without it? Yes.
Am I prepared to reduce the living standard of my family to do so? To my shame, no.
Why shame? I think that a lot of people live far above the living standards of so many that if we shared a bit more everyone could be a lot better off. However, the realist in me knows that there are too many who would take advantage of the situation that the money would not get to those who most need it. Instead I earn as much as possible and donate through standard charities particularly supporting the causes I think most worthwhile.
Am I a technical mercenary? A coder for hire? I guess so.
-- Stop your grinnin' and drop your linen...they're everywhere!!!