When I think manipulation I immediately picture marionettes. You generally can't manipulate someone the way you can pull the strings on a puppet, the person still has some sort of say in whether or not to allow you to 'manipulate' them.

The 'moral event horizon' you mentioned in the first post is the point in which you use someone as a means only, or against their will.

If you lie or omit information in order to attain desirable results, the cause may be from a perceived imbalance of power.

Manipulation in regards to human interaction seems like a dirty word, maybe the people that claim your being manipulative are manipulators themselves.

"What is the difference between someone who is convinced and one who is deceived? None, if he is well deceived." - Friedrich Nietzsche