If you find a flight that goes from A->B->C, then returns C->B->A and it is much cheaper than the B->C, C->A run, they prevent you from taking advantage of this by clearing your e-ticket if you're not on the plane from A->B. Can they stop you from getting on the plane at B if you have a paper ticket, or is paying the 25 dollar paper ticket fee a legit way to beat the system ln this one?