I am still way under a thousand clicks with a D600 sn 304**** purchased a few weeks ago. I have already wet-cleaned the sensor right out of the box after fully charging the battery, and since then have only been dry-cleaning and moving around a few dust spots. Note there is a typical dust spot visible in the upper left of this bluesky f/22 test image done on location. For me, it is easier to see dust, pollen, sand, oil spots and smears against a blue sky with an iPad retina display on location. There are always tremendous amounts of palm tree pollen grains in the air out here. Pollen grains cannot be dry cleaned off the sensor and will look like oil spots, and both must be properly wet cleaned off the sensor to avoid smears. And the salt-water mists at the beach also ultimately find there way onto the sensor. Bottom line is that I have found it impossible to shoot on location here with any Nikon DSLR, and with changing lenses, not to pick up a boatload of unwanted stuff on the full frame sensor. In any case, in time, I will inevitably soon collect more dust or shutter oil spots on this D600 sensor, and then I will once again dry or wet clean as necessary. If I should see an unexpected accumulation of dust and oil after any shoot on this sensor, of course I would send the body back to nikon immediately while it is still under warranty. As a baseline for my D600 and my other Fx bodies, I follow a simple routine: before a shoot: I always do an f/22 test and if necessary clean the sensor. For wet cleaning I use visible dust ultra mxd-100 Vswabs with Vdust plus and/or sensorclean solutions. I use a giotto rocket blower and arctic butterfly for pre-shoot dry cleaning. And most important, at the end of every shoot, I use the f/22 bluesky sensor test to determine where dust or smears have possibly located during the shoot, which greatly aids in retouching selected RAW shots in Aperture. Good luck.