Upload & Sell: Off
Generally I don't. Especially if
1) you will end up printing the image, where the noise is lost in the paper texture or ink dots
2) you downsize for web use. The noise will go away in the downsizing
I care more about chroma noise than luminance noise. If there is just a little noise visible at 100% I will give just a touch of chroma NR (like 5 points worth on the LR slider) to clean out color impurities, and then leave the luminance noise as is.