Having assembled bikes at a shop that faces every bb and head tube on the new bikes they sell, my experience is that almost every bike, up to the most expensive, need to be faced. This is particularly true of aluminum bikes, which often have significant distortion back by the chainstays. There are lots of bikes running around with minor bearing misalignments due to this. The good news is that threaded cups will average out the distortion. Doesn't mean that it isn't having an effect.