I also agree that D7000 does have focusing issues. I had to fine tune adjust all my lenses. When they were on my D5000 they worked perfect. So every lense I get I get to go through the fine tune process. Other than that it is excellent camera, but I did pay a chunk for it should not even have that issue. My friend has the D600 and has no issues with oil on her sensor as I asked her that right away as I thought of upgrading to a D600. Yes, I think Nikon needs to admit when there are issues and do the RIGHT THING!
The D7000 does not have a tendency to backfocus. Both the D7000 and the D7100 have an autofocus fine tune feature in the event that your particular lens and camera combination need to fine tuned or corrected.
In my case, yes. I had the same issue and main reason I decided to buy this camera. Loved the d7000, but focus was a huge pain. So far so good with d7100. Using same lenses, no focus adjustments and all looks good.
I had to return my original D7000 as it would backfocus and no amount of fine tuning could compensate. I wouldn't call it a tendency. Rather, there seemd to be a number of D7000s with the issue. The real problem is that Nikon never acknowledged it or helped isolate the cause and a proper fix for the bodies that were affected.
Regardless. the D7100 is it's own beast and I will be watching the 1-star ratings for the kinds of issues people are having and the number of them vs 5-star ratings. I was going to pick up the D600 until I saw all of the posts with oil spots. Who knows, maybe Nikon quality control has pulled it together.