Let the mud sling. Possible discussion questions.
What is a "dirty trick?", and how is it different than negative campaigning?
(My suggestion would be to differentiate...
..."comparative campaigning" (fair assertions that Candidate A is better than Candidate B)...
...from "negative campaigining" (fair attacks on Candidate A's record or character)...
...from "dirty tricks" (ethically questionable attacks on another candidate)).
Which candidate has used the most dirty tricks?
Which candidate's tricks have been the most egregious?