Ill try to get some pics, but its on a friends camera.
Everything you're saying makes sense and stuff. But it rained like 4 hours before we went so It wasnt dusty out. There wasnt fog/mist or anything. It was a very clear night.
And this is just a point and shoot camera aswell. About 300 bucks and its about a week old.

It was taking fine pictures while I was walking there, on the way back the spots started appearing, then when we left the parking lot things were fine again. I really doubt dust was the cause, and same with something in the camera.. so is there any other reasons spots appear?

Ill try to get those pictures soon