If you donate money to Greenpeace and get a tax deduction, is your act less moral?
Indeed it is, at least in the perception of other people, according to a new psychology paper on the "tainted-altruism effect", which suggests that charity in conjunction with self-interested behavior is viewed less favorably because we tend to think that the person could have given everything to charity without taking a cut for themselves.
Of course, plenty of people give to charity or commit charitable acts without thought of any benefit. Perception about altruism is in the eye of the beholder. And Greenpeace is just an example, you could think about churches or, in the case of one experiment below, a man who volunteers in order to impress a girl.