The negative tone of much contemporary politics in Canada, and even more the case in the United States, is an issue of concern to people from all sides of any given issue. It seems to me, based on prolonged observation, that there is a simple remedy that would go a long way to address the concerns of those lamenting the balkanization of our political discourse: use people's names.
Even if you don't like someone, or their views, show them some respect and use their name. As someone who has trained as an academic I'd be interested to see a correlative study linking the use of derogatory nicknames with the appreciation of complexity in politics. Painting issues in black and white is rarely a good way to accommodate the complexity of the world we live in. Painting policy alternatives, like a given airport tunnel project or piece of legislation, in black and white is even more unlikely to reflect anything resembling their true relationship with reality.
The fundamental point I always aspire to bear in mind is that people of good will can, and will, disagree on any given issue. Our system of Westminster-style democracy is not only designed to accommodate such disagreements, it is dependant on the adversarial contest between diverging views to develop a working consensus. This is perhaps even more the case in our pluralist parliamentary model, as opposed to the unique duopoly the Americans have developed. A substantial majority of our fellow-citizens are good people, so those engaged in our political discourse, whether they be politicians, civil servants, journalists, commentators or concerned citizens, deserve the same assumption.
The use of nicknames, whether simply shorthands or the actively derogatory, is obviously a continuum. However, in order to avoid slipping into the derogatory, or the grey area in which one could be perceived that way, use the simple alternative of the proper noun. So instead of 'Slitherman' or 'Harpo' I try to use Mr. Smitherman or Mr. Harper. In the latter case why not acknowledge his earned title, and call him the Prime Minister? He is, after all, whether I like it or not, and he deserves to be.
In short, I have resolved to combat trolls on the internet and incivility in my speech by aspiring to use the simplest of formal courtesies - the proper name.