I dont really clean my stuff. As I tend to keep things quite neat and tidy when working and tear peoples arms off before they can even get near the screen to poke it.
If the odd bit of something does need cleaning I use i tiny bit of water on a soft damp cloth.
The MB with glossy screen is easy to clean because of the glossy screen. I dont clean the entire screen though just the spots thats need taking off.
On my PMG5 I have a matt cinema display which is much harder to clean but still only use a slightly damp cloth. I rub it so the rubbing action is doing more of the cleaning than the water (if that makes sense)
I dont like using chemicals and stuff although Vodka works quite well used it small doses as it evaporates pretty quickly.