Im trying to understand what you really want to say. But I didn't. I try my best to understand and I hope I answered your question.

I don't know if there's a way to positively conclude on dealing with either manipulation or good intention ahead of time. This is partly because many people can't tell themselves whether their intentions are totally clean or whether they're engaging in self-serving behavior. Most of us are very skilled at self-deception and some people tend to hold beliefs that bolster a positive self-image without really examining how accurate those beliefs. And on my opinion, maybe try to be self-aware of your own needs and desires. When you feel that someone is looking for something from you, and maybe not being entirely honest about it. Try to base the decision on your own desires (including your desires about the relationship--maybe the relationship is more important enough that your willing to overlook some minimal amount of problematic behavior).