My brothers almost 3 yr old dog Vegas had recently been trusted with the run of the whole house but the other day my brother came home and Vegas had been on his bed and chewed his whole duvet into pieces. He is an extremely well exercised dog so I don't think that is the reason.
He did chew when he was younger and as he hadn't chewed anything in the kitchen/diner for like the past year he thought he'd let him have the whole house while he was at work but what a mistake that was.
My brothers attitude was great though he just said at least it wasn't the leather suite in the lounge, back to the kitchen/diner for Vegas now