Why need a clean samples?
If you’re fixing a very high-resolution image with a grain, it will be tough to try out the same color that you need. You may find that you will be getting the colors from the source instead. The obvious way to get a better average color is always to alter the Sample Size. When you choose the Eyedropper tool (l), you’ll see the Sample Size inside the Options Bar. Select a higher sample size for higher resolution and noisier images.