fidelia highlights an important point:
INFJs put others at ease and attract the downtrodden and the outcasts, despite not always wanting to be in this role. I certainly have seen people (myself included) cross over INFJ boundaries because the INFJ seems more welcoming and open than they really feel. It then may not always be a quest to save other people, but at times it is other people looking to be saved or loved. This is an important distinction and one oft-overlooked.
I think this is a source of negativity aimed at INFJs, since it is the source of hurt feelings and feelings of betrayal. INFJs give so much of themselves that it is almost expected that they continue. When they create boundaries to protect themselves, people get angry. People will then lash out with accusations of selfishness, malice, and manipulation.
Also, I still don't think it is about an INFJ wanting to be saved themselves. While this may be true for some individuals, I don't think it is indicative of all or even most. My INFJ ex often neglected himself to care for others and I think he individually was harmed, however, he certainly wouldn't have wanted to be saved. He didn't need to be saved, however, I think he did need help at times. However, he was far too independent to be saved and he enjoyed self-help and self-healing. There were many times where I offered to give help or insight and he would say he wanted to think it over on his own. This process can be quite frustrating for non-INFJs because of the lack of transparency (it was often the case that he would come back with an entirely new perspective).
This, of course, isn't to say that any sort of saving behavior is solely INFJ. However, the functions of the INFJ endear them to these sorts of qualities in a way different from other types.
I still identify mostly with f because I'm a woman I think. 
