I've been experiencing a problem with the palmrest of my 2011 unibody Macbook Pro and was wondering if anyone had advice on keeping it clean. On the left palm-rest I've noticed that there's subtle accumulation of dirt being transferred from my hand to the aluminum unibody. My hands are generally clean when using the laptop, but I'm sure there are times when there's some dirt that's coming off since I use the device 8-10 hours a day. Right now it's very tiny dark spots ... but I can imagine over time it may become more visible. Does anyone have any advice on how to clean this without scratching the unibody? Just rubbing with water doesn't seem to be sufficient to clean the surface, but there's also no apparent texture to the small specks. Any advice?