I hesitate to even say this but...this is pretty common. I can't say that they "all do that" but I suspect they do. You can use some spray on brake cleaner and steel wool to scrub the rotors (be careful, you can burn your paint) but in a few days the Nike Swooshing is back again. I find the best thing is just plain old soapy water like you use when you bucket wash the whole bike. Wash the inside and outside of your rotors.