Originally posted by westcoaststyle
don't paint it, you'll ruin it's cooling properties. Painting it will add a layer of insulation to it; therefore, adding that much more between your IC and the air running inside of it.
Painting an IC is stupid, it reduces the ability of the IC to cool the air. 
It's not really going to be enough to affect anything, about the same as people putting wire mesh in front of the IC.
I've seen people do it for the stealth look so you can't see it, but if you're driving beside someone they won't be able to tell.