Unlike what a lot of people would have thought, Photoshop smudge tool are great for painting. But before using it, you will need to enable one option in the brush settings, which is "Scattering". "Scattering" is the option which make the smudge tool to blend colour automatically and simulate wet effect in painting. In my case, I use this smudge tool a lot for blending colours of cloud in landscape painting. | mclelun