Realtors heavily use social media to advertise nowadays
All that needs to be done is to go on youtube, facebook, twitter, etc and start making posts about how bad the neighborhoods are that are in a bubble right now ( Mainly the GTA (Greater Toronto Area) and parts of Vancouver atm ). Complain about noise pollution, crime, traffic etc make it the areas are as unattractive as possible to foreign buyers.
The housing market is already taking a plunge, but it hasn't been hit hard enough. When buyers see negative comments on social media they will hesitate to buy and force realtors to lower prices even further possibly triggering a huge drop. The Housing market is the only thing holding up the Canadian economy. If you want to see Canada crash and burn this is your chance.