I think all humans are manipulative. You need to do that to survive in a social group. So I don't think it is bad.
But then there are manipulators who manipulate people not just to survive in a social group, but to gain something from that person, to keep a person under there control, make them emotional depending. That kind of manipulation creeps me out. When that happens to me, the ground under my feet disappears. It is because in default I trust people, I have to be able to trust people. I also have a good feeling about what is true and what is fake. So when I find out that someone was manipulating me the whole time and worse that he has been able to stay under my radar, it freaks me out, it hurts a lot. It is because this means my radar system has failed and I start to doubt my whole decision system. I have to reconsider every past event and to reanalyze every single person in my life to redecide what is true and what is fake.
But I will never trust that person again...
I think this is a good example of why I think I'm INFP.