You miss the point completely, its not about defects. Yes there are problems with Nikon, Canon, Sony, everyone. The question is how they treat their customers after the sale. If I spend $2-4K for a camera or $500 I would like the problem fixed, if not in the first try then the second and not by sending it back repeatedly. Nikons customer service is abysmal in the USA, some fanboy may offer "oh I had a great experience", sure there are great individual experiences but overall its bad. If you don't like what I have to say read through Thom Hogans site. Somebody from Germany or GB may have a very different opinion of Nikon customer service. Perhaps its good there.
I can tolerate genuine mistakes, but make it right. Repeated cleanings are not doing it on the D600, fix it, replace it or whatever but let the individual who gave you his hard earned $2K go take pictures and not have to worry about a dirty sensor every 100-200 shots.
Excellence is an art won by training and habituation. We do not act rightly because we have virtue or excellence, but we rather have those because we have acted rightly. We are what we repeatedly do. Excellence, then, is not an act but a habit. - Nicomachean Ethics