Ethics 
 We might add more content about the ethics of vote trading. What I seem to notice is widespread acceptance of the practice, as long as the proposition is not made in an unseemly way. I went to a Ford Fairlane convention where there was contest involving, if I remember correctly, 13 categories of cars, each with a separate prize: categories A through M. A guy whose car was in category G went around to people with cars in the other categories, offering to vote for their car if they voted for him. In that way, he picked up 12 votes, and no one seemed to have a problem with it. 

 Perhaps one of the reasons why it is accepted is that it's so hard to enforce prohibitions against it. I will look for more info about this.