In Guide to Mirrorless, I document a damaging contrast bug with the Sony NEX-7 that came and went while shooting a comparison. The bug is independent of lens and aperture and occurs with the latest firmware. Included are RawDigger histograms to show that the bug is independent of raw converter.
This bug explains several series of severely low contrast images I made in NYC recently. These really surprised me, but I rationalized away the problem as due to shooting through window glass, even though other shots were fine. Now I believe that the window glass explanation was not involved and this was purely a camera bug.
Nasty stuff and one more reason I will wait for a new model (NEX-7N or whatever it will be called). See also my longer term perspective on the Sony NEX-7.