I like the smell of a brand new deck fresh from the wrapper but the cards are just far too springy decent plaming. I have to agree with doing a few fiffle shuffles and doing some slights just untill they feel right.
Saying that there are good and bad points with using new or worn cards, for example with a new deck as Seige pionted out, double lifts are far easier as well as glides.
Also this is just a theory, but I dont think cards get worn as such,yes the faces will get a little greasy but i think they soak up the moisture in the air which causes the loss of "springivity" (thats definately not a real word), i feel an experiment comming on here!!!
Im just about to stick an old knackerd deck in the airing cupboard now.