I use my blackberry to view PDF instructions and photos while working on my jeep or motorcycle, i just wipe my greasy fingers on my rag and then trackball away, funny thing is that it looks brand new and not even remotely black like some of those pics show...
i think that the trackball is bound to get dirty, but for how much they cost, change it once a year/6 months etc and be done with it, or you could be like me and not really give a crap
