While Obama and McCain said that they would run clean campaigns, that promise has been broken. McCain seems to have gone negative first and to such a degree that even Karl Rove was critical. To be fair, Rove was also critical of Obama.
People generally say that they do not like it when candidates go negative. However, it seems to work quite well. For example, while Palin helped out McCain’s numbers, it seems likely that his switch to negative tactics has paid off as well. This raises the question of why such tactics work, even when people say they do not like them.
One option is that people are lying when they claim not to like them. Perhaps people think that they should say they do not-after all, liking such things is not very nice. If people secretly like negativie tactics, then this would help explain why they work.
Another option is that people truly do not like them, but they influence their beliefs and behavior anyway. To use a non-political example, a person might not like mean gossip. However, his behavior and beliefs could very well be changed by mean gossip he hears around the office. Likewise, people might not like negative tactics in politics but might still fall under their sway.
A third option is that people do not like them, but the nature of political races still makes them effective. To be specific, in the case of the Presidential race there are effectively only two viable options: Democrat or Republican. If both sides go negative (as they are), then the side that does it best will have an advantage. People might not like the negative approach, but if both sides are using them, then their dislike really has little impact. People could, of course, express their dislike by voting for a third party candidate. However, it is clear that most people do not dislike the negative tactics enough to take that option. Perhaps it is because supporting a third party candidate is to embrace certain defeat.