Do you think intent mitigates the value of a good deed?

People (I am one of them) often suggest volunteering to others as a way of feeling better about yourself, meeting new people, looks good on a college resume, etc. These are self-serving reasons for volunteering. If someone is motivated to do volunteer work for what they personally get out of it, do you think it in some way that lessens the value of the act of volunteering? Or does the value of action of service to others or to a cause stand on their own merit, separate from intent?

This question is beginning to feel like “if a tree falls in the woods…”