For this test I placed a small piece of paper chad on the rear element. I wet the piece so it would stick to the element. It's image is clearly seen in every out of focus light. Each light is a small point source. While dabbing the wet piece of chad on to the rear element I also left an obvious finger print smudge. That's also seen as smaller spots around the chad.

The lesson here: If small lights are OOF in the photo make sure your lens is clean.

After cleaning off the back side of the lens I still had a few small spots. Cleaning the front element took care of most of the remaining spots.

I still have one spot that shows only on the upper lights. Looking into the lens with a light, I see there is one prominent dust speck on an inside surface. Oh well...