It works, I used it at church as a backup camera, then I noticed it has dust on a mirror and the battery was going low, so I put it in a sock drawer, I have too many more expensive cameras.
I personally see it in the screen and know cameras to know a bit of dust is on or around the lense area, I only used this camera as a back up for video producing and it made very little difference. I know it's there cause I see it in the screen.