I was forum surfing at DPReview and found a nice Capture NX tip to remove dust spot. Nikon Capture NX does not have a healing brush or clone tool like Adobe Photoshop. Typically dust spot removal in Capture NX involves selecting the dust spot using lasso tool, colorizing the selected area with color that is the same as the background, blurring the edges with some feather on the selection. This neat new technique uses distortion control (Adjustment -> Correct -> Distortion Control) instead of the Colorize tool. And it works!