On my Nikon D7200 with only 1,000 clicks. I just noticed some dust and splatter with some recent shots so I took a reference photo on blue sky at f/22 and there was more then I thought. I broke out the visibleDust swabs and gave once over to get the dust out but the splatter took some doing over a couple times with wet clean to remove it all and applying a little more pressure on the final swipe to remove the remaining splatter. My D3300 has a few thousands clicks and no signs of dust or splatter. Anyways thats that,its probably cleaner now then the day it left nikon factory but the splatters are not easy to get off and hopefully this will settle down after some use.Sometime I wonder if there some over zealous use of some sort of lubricants on the assembly line.The D600 issues was In its own but a friend of mine has a D5500 thats pretty new and his camera is flinging a lot of crude all over his sensor and know mine has a few spots but nothing that greatly concerns me unless it gets worse.