Manipulation.

I suppose it could be a sign of particular types of intelligence, maybe some correlation with "typical" smarts. Id link it more with charisma than anything, but its a very vague concept that most have a very specific view on.

Its a tool, so can be used for good or, more frequently, not..

We manipulate our children to no end, and I dont see much of a way around that while still.. you know.. raising them!

Bartering is also enjoyable to a lot of people, same with poker and a variety of games. There is also marketing and propaganda. Im not sure any are "good" or "bad," except in application.