Review on ELP Camera USB 2 Megapixel with Black Case and 3.6mm Lens: Ultimate CCTV Surveillance Solution for Machine Vision System, Home Baby Monitor, and More by Cris Drew

The image had two black spots when received. Cleaning the lens did not solve the problem. I cleaned the sensor which is easily accessible with the lens removed. I used a Q-tip and rubbing alcohol, then gently blew it out with compressed air. It worked and now the picture is clear. My guess is that the sensor isn't sealed that well against dust ingress. I measured the angle of view at 84 degrees, which is less than it should be for a 3.6 lens with the sensor it's supposed to have. Image quality is ok.