I'm experiencing the same issue with my Smok G-priv. I'm sure we all get some juice on our mods, and nicotine is the culprit. Nicotine has some sort of paint removal quality, and it's almost impossible to avoid having a minor spill every now and then. It does beg the question that if nicotine does this to paint, what's it doing to my lungs? Anyway, a great deal of manufacturers unfortunately aren't producing finishes that can stand up to this. Unless you have a pure copper or brass mod, you're likely to experience this problem. Luckily, it's a purely aesthetic issue and will not affect the functionality of your device.