jcboy3 wrote:
Depth of field is not the issue when dealing with sensor dust spots, and only marginally when dealing with spots on the lens. The actual mechanism is simply that the larger aperture will focus light from a wider path through the lens, and the spots are thus relatively smaller. Stop down the aperture, the light path is narrower, and the spots are proportionally larger and thus more visible in the image.
You are welcome to believe whatever you wish.