Technically it does have to be scratch free. If there are any signs of use sprint can refuse to exchange it for a different model. The reason is that phones returned within 30 days are sold as pre-owned phones for half the retail price when someones phone is damaged beyond repair, lost/stolen and have no insurance or rebates towards a new phone available. Solution is dont scratch it at all or if you do and worry that they wont exchange it try and convince them something is wrong with it.