Thanks for the tip Mark. I was under the impression that they had to be donated if they were actually used. As opposed to say bought and returned without ever being used (or bought and never picked up, etc..) This was probably based on something told to me at Sleep Country some years ago and bolstered by what I experienced crossing the border US -> Canada with mattresses.

I have been told on two separate occasions by border officials in Canada that we're not allowed to bring used mattresses up from the US. Both times I was bringing up new mattresses, so it was part of their questioning at customs.

When doing research for mattresses back in 2009/10 I stumbled upon a great forum which I can't remember the address for any more. But it had an amazing array of information on all the different types of mattresses and the various things people do to each type to dial in their "perfect" sleeping platform. I'll have to see if I can find that again, it was an invaluable resource.