On one hand my willpower is strong, on the other hand I'm very pragmatic and flexible. The contentment of people around me and a pleasant atmosphere is usually more important to me than having things going "my way". This/that can usually be done in several ways, and if someone has an opinion that is stronger than mine then I'm commonly willing to say OK, sure. I care more about the long run outcome.
It is definitely possible to manipulate me. I'm too nice. I'm even aware and allow it, simply because I see that the matter is of great importance to the other person. This has got to be happening without me noticing it but I can't really know that soo...
It's a good skill I think. I use it too. Build sentences that would lead towards what I want. Angling. One can imply, make connotations, add a positive/negative tone. Create emotions. Manipulation itself has a negative tone to it because yes people do use it maliciously, but it can be practiced cleverly for any cause.
It is not likable though, when someone appears as manipulative. In my opinion the attempt is a failure if it is obvious because it adds an unpleasant character (being sneaky). The success is in achieving the goal unnoticed. Because it is also possible to simply be straight forward about things, right to it. Actually this is so nice.
People make mistakes when they assume others to be stupid. Anyone can look stupid, doesn't mean that they are. Don't make this mistake, is what made me think about this in the first place.