Apple Store Macbooks? (Score 1)

If it's just a case of body grime reacting with the plastic, wouldn't this yellowness become rapidly apparent at the apple stores, where there is almost constant use of all of the macbooks? I'm especially curious about the new NYC apple store, since its computers must be on 24/7, so heat as an issue would also be magnified there. Do they just replace the yellowish ones with new macbooks? Or are they just very fastidious with their cleaning process? I haven't noticed any yellowing of computers the last time I went, so I'm inclined to believe the nicotine theory. Can someone who works at an apple store shed some light on the situation there?