Here in the UK I LOVE those companies that send us BS through the mail. So long as they give me a pre-paid envelope to send their crap back to them in. I really enjoy stuffing their own blurb back in that envelope, knowing it is going to cost them the return postage.
It is one way, as LH says, of costing them money, maybe if we all did this it would become uneconomical for them to send this crap out to us.
I have seen something, somewhere, which suggested that we should all charge these companies for the time taken to read and evaluate this s*%t (their product), as they are asking us for our opinions, and we are then acting as consultants, and should be paid a fee based on an hourly rate.