I used to work in a jewelry store and learned that using perfume or cologne can remove glue and marker stains better than just straight alcohol or anything else for that matter. It has an intense concentration of alcohol. It's pretty neat how easy it works. Try it on your skin. Use a sharpie on your arm, then spray cologne, it literally runs off your arm.
P.S. Just noticed I awake this post from the dead.
Sharpie doesnt stick permanently in Shiny surfaces like shiny plastic...surface has to be free of oil for it to stick. I tried to use sharpie to design my tpu case and was disappointed.