Originally Posted by ElmhurstNick
What I don't understand is why Mr Chicken sometimes repeats the offer for the same price at checkin. It happened to me today on ORD-DEN-OAK - I had upgraded the 777 ORD-DEN but was content with 8D on DEN-OAK. Mr Chicken asked me if I'd like to pay $130 to upgrade.

Why would I pay $130 to upgrade if I didn't want to use 2 500-milers to upgrade??
General members can't upgrade discount fares, so this offer would be of value to them. I suppose there might always be a 2P or above who might not think it through and buy the overpriced upgrades.
Oh, also, if you have zero in your bank, this is the only way you could "buy" fewer than 4 certs-worth. That might also be of value to someone.