Waxing your car every three to six months can help to protect it from the elements, keep it looking new, and help raise the resale value. In short, waxing helps avoid unsightly blemishes caused by time, weather, or other conditions. Blemishes on a photo also make it look old, ugly, and worthless.
In the past, when all images were scanned, many had problems with scratches and dust that were captured or showed up during the scan. Now, you might think that with digital cameras that is a problem of the past, although that’s not necessarily the case.
Proper camera maintenance will help you avoid dust and spots on your CCD (sensor). Otherwise, the spots will appear, especially at high apertures and on mid-tone backgrounds such as skies, walls, etc.
When the sensor spots appear, you should carefully retouch them, without causing new problems such as obvious cloning blurs. You should retouch the spots by using a soft, feathered cloning tool to sample close-by areas with the same texture, using a tool with a diameter similar to the spot’s diameter. You should check that your cloning efforts blend into the image both when magnified and when viewed at normal size.
Here is an example of an image with blemishes:
Example. On the right, you can see the sensor spots provoked by dust on the camera’s sensor.