Had MBP for 3 weeks, I have been using just dry tissue as I didn't have any liquids like distilled water (in UK all tap water is so scaly it leaves so much smudge afterwards) as I didn't know which one to use. Apple support says clean with liquid, but it doesn't mention what the consequences of not using liquid and just using dry medium. I was recently told cleaning with just dry medium can scratch the screen as the dust can act as particle... But then I wasn't thinking of this because on some TVs the manual for cleaning its screen was not to use any liquid whatsoever. (e.g. page 6 of document here for my TV http://downloadcenter.samsung.com/content/UM/200907/20090707111323906/BN59-00910C-01Eng.pdf) Is this due to difference between different materials for screens of TV and glass MBP? Is Glass screen on MBP easily scratched if you didn't use liquid?