What I think is that we all have narcissistic tendencies and we will go to great lengths to hide our real motivations. That is why codependent study is so important to me. It has taught me to really evaluate my reasons for doing things - including others. Is it so that I can just feel better about myself? To relieve my own uneasiness? To make me feel virtuous?
The idea of codependent behaviors as narcissistic is a valid one as we often find our identity and worth in how much we do for others.