Finally got around to taking the cam apart again to refocus the lens. Wasn’t very difficult. The good news is the picture now is great. Probably better than when I got it.
I took a photo of the oil I’m talking about. I also felt it with my fingers to confirm that it IS oil. (It’s not just that the plastic is a little shinier there for some reason, for example.) The oil is only on the bottom part of the lens threads – the portion that is threaded from the factory.
Since you seem fairly comfortable taking the cameras apart, @mobstaj, I’m curious to know whether you see a similar oil on your cameras. I would guess that it’s there on yours, too.
I’m pretty convinced this is what eventually fogs up the glass, especially since it seems like this IS an issue that develops over time. (Mine didn’t look as bad as yours, but mine is about a year newer. This person also reports that the haziness developed over time.
Anyway, here’s what mine looks like. I took a video because the oiliness seemed to show up better. It was harder to show in still photos. You can see that the bottom half (top in the video) has a slick oily substance.