When I was little, I remember trying to manipulate Mom into letting me set the table with cups, saucers, salad plates, bowls, the works. While she was wavering, I tried smiling my sweetest smile and saying, "I'll wash 'em!" Yeah right. Even as I said the words I knew I didn't mean them. It was all about getting my way that moment. Later on, I could find some way out of this hasty promise.
Fortunately, I didn't become a master-manipulator, though I've got to admit that there's times when I have manipulated my parents. And lately I've been sorely tempted to try the "it's either her or me" trick.
In case you come across a manipulator (or even one in the works), this article presents some ways to tell. Books have even been written on this subject! (George K. Simon's In Sheep's Clothing: Understanding and Dealing with Manipulative People is one example). One excerpt describes the characteristics of a covert-aggressive personality.
The bottom line? Don't get fleeced. And don't fleece others!