This is more of a Tip than anything. If you use Visualize Spots, that is helpful AFTER you've taken the photo. What about before? I shoot product photography and I've found that if I boost the Dehaze up as high as it will go, it will instantly show me dirt, smudges etc which I can clean off before I commit to an image. It works similar to Visualize Spots (set really high) but you see for real where the schmutz is.