If you really want to see dust, take a photo of a clear blue sky, with a small aperature, then view the image on a computer at 100%. You will need manual focus at infinity, as the camera will not focus on the sky.
Turning the camera off while changing lens in a SLR will help to reduce the static attraction of dust, but not prevent it.

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figuring out how to get rid of it in such a humid climate...now there's a problem to reckon with. 
