So why do such a thing? Part of it is constructing a distinctive brand identity. But also, Adbusters has a specific socio-political goal: to influence and to change the opinions of the audience in order to ensure the continued existence of the planet! And if this involves making the audience feel bad about their lives, well, it's frankly only doing what advertisers have done for well over a century now.
So that's the why, but what about the how? By way of example, check out this excerpt from nihilistic horror author Thomas Ligotti (highly recommended, btw) and an excerpt from an Adbusters straight after. The lexis and position and feeling of utter bleakness is rather similar, but most of all, it is the construction of self-hatred in both narratives that is especially potent. Therefore, it isn't much of a stretch to argue that Adbusters uses the conventions of the horror genre to instil a sense of dread and helplessness in it's resolutely middle class target audience!
They were as strange as I had dreamed, more closely resembling devices of torture than any type of practical or decorative object. Their tall backs were slightly bowed and covered with a coarse hide unlike anything I had ever beheld; their arms were like blades and each had four semicircular grooves cut into them that were spaced evenly across their length; and below were six jointed legs jutting outwards, a feature which transformed each piece into some crablike thing with the apparent ability to scuttle across the floor. If, for a stunned moment, I felt the idiotic desire to install myself in one of these bizarre thrones, this impulse was extinguished upon my observing that the seat of each chair, which at first appeared to be composed of a smooth and solid cube of black glass, was in fact only an open cubicle filled with a murky liquid which quivered strangely when I passed my hand over its surface. As I did this I could feel my entire arm tingle in a way which sent me stumbling backward to the door of that horrible room and which made me loathe every atom of flesh gripping the bones of that limb.
(Thomas Ligotti, Dreams of a Dead Dreamer 1989)
Or maybe what’s really terrifying are the microbeads in the toothpaste you are about to purchase, which brightens your smile and pollutes your waterways. Maybe it’s the toothbrush made from non-recyclable plastics. Maybe it’s the soft plastics that you are wearing right now, all the petroleum products that went into your shoes, all the child labor and poverty labor that went into the clothes you are wearing, or maybe it’s the propylene glycol in your deodorant or the BHT in your cereal or the palm oil in your mayo. Maybe what is absolutely chilling and blood-curdling is the fact you are so used to these crises and disasters in and around the things you eat, wear and use that you learned long ago to ignore reality. To recognize this reality would result in paralysis. Worse still, you feel powerless to do anything about it.
(David Joez Villaverde, Save The Planet: Kill Yourself: A Guide To Living In The End Times, excerpted in Adbusters 125)