I think manipulation is fine if it's use in a way to ward/deflect others from oneself. You appear and show that what you want others to see is to trust you and leave you to your own business. Mild manipulation is fine. You ultimately allow reality and your actions to be the true teacher. I believe truly good intentions to benefit oneself and others end up working out anyway if that's what you truly want. Of course misunderstanding may result, but whatever.
Now interesting about manipulating someone to fall in love with you is more grey. While in an ideal world, our feelings would effectively communicate telling this person has the values and perspective I would be most compatible with in life, but it isn't always the case. And for many people, not many are really in psychic, ESP, soulmate/twin-flame belief system. Some men are simply into hot women. If the desire is being met, that isn't bad manipulation. So to be quite explicit, if a woman makes herself more attractive with make-up and it gets the guy and it's her goal to get in bed with him. I don't see that as an issue, as long as there isn't any underlying strings attached.
However, a lot of people don't end up being that simple and is where my main issues come with manipulation. To intend a unforeseen goal that the other party won't realize until most likely he/she is caught up in a moment and his/her actions are limited perhaps limiting to all/most choices as harmful or hard to discern which is and which is not. For as if maybe the woman really also wants this man's child but also guilt-trips him into taking of that child even though she never shared such statements with them.