Suppose that you're traveling on a full-fare refundable ticket, and volunteer to be bumped for some vouchers/compensation, etc. You're then rebooked on a later flight. Can you decide not to take that flight, and still get a refund for the ticket? Or is a ticket non-refundable after check-in?

You see what I'm getting at -- is it possible in effect to get something for next to nothing (just a couple hours at the airport in return for bumping vouchers)?

Just curious.