Vehicles that have been in accidents and are written off by insurance companies are bought by someone who hammers them out, paints them, and sells either to a dealership, or directly to some unsuspecting consumer. This sometimes results in horror stories of cars breaking in half because they hit a big pothole. Huge profits are being made and it is the consumer who is suffering. For most Canadians, there is no way of finding out if a vehicle has been salvaged. Disclosure laws are basically non-existent.
Dealers have no legal responsibility to disclose a vehicle's history.
No one is obligated to tell you if a car had been written off by an insurance company, even if you ask. The U.S. already has salvage laws and they are getting tougher. This means that Canada may become more of a dumping ground for these salvaged vehicles than it already is. If you do find out, there is really little that can be done. In some cases, if there has been a serious misrepresentation by the seller, you might have a remedy under general consumer or business practice legislation, and your only option is to consult a lawyer.