I don't remember the screen of my 30D ending up quite as 'smeary' as the 5DmkII screen does... because of the different size, different coating... who knows.
I certainly agree with this. The 5DII has unfairly and wrongly termed a dust magnet (sensor), but the LCD screen seems to be a grease magnet.
At first it annoyed me, now I just ignore it because I'm thankful I don't have one of those ugly screen protectors that I see on Nikons. Canon has gotten the screen protector right but Nikon sure hasn't.
Just for those that buy an additional screen protector - the Canon has a screen protector - no need to add another one because the Canon one is very tough.