Orbs In The Ice House

My camera lense is clean. I never see these spots when I'm taking pictures, but when I veiw them later on the camera or the computer, there those mysterious orbs are! But only in wierd places at night or something. I snapped this one in an ice house at Garnet Ghost Town up in the mountain tops.
Here is the same picture with the brightness adjusted on my computer. I just wanted a picture of the inside of the ice house, because it was part of my adventure in the old mining camp.

Could be back-scatter or near-camera reflection, but just why and how do these things pop up in certain locations only? Ask my daughter about the time we were taking photographs at night in New Mexico. Her husband took a picture out the car window and she saw orbs in it. She took the camera and shot the same scene and there were no orbs. They traded turns taking pictures and his all had orbs and hers didn't. Knowing that she married a skeptic, she blithely suggested, "Hey, let's go back to the motel and take pictures in the dark!" The Cool Man was quick to nix the plan.