There are people that chop them in every year - not even the dealers can understand the logic, but aren't going to complain! They do make great bargains for the second owner - usually they have only been used a couple of times, expensive way of camping!!
Others will be ex-demonstrator vehicles, they have been driven up and down the area on test drives, driven to shows in the area so cannot be sold 'as new' - again they make for bargains!
Be very suprised if any are ex-hire fleet, they have a much longer life span than one year! Hire would be very expensive otherwise.
Find one you like and grab it! You will more than likely save the best part of ten grand, just for having a motorhome that has been driven about or slept in once or twice.