by dat8962 » Feb 8th, '07, 23:21
Cards fan best when they are new and as they pick up grease and dirt, so they fan less easily and unevenly. The use of fanning powder can restore some of ability to fan but again it is dependant on the overall condition of the cards.
Now - you really should get some new decks if you're still using one that's some two years old

Most of the cardies will bin their decks within weeks or even days on some occasions.
Member of the Magic Circle & The 2009 British Isles Close-Up Magician of the Year
It's not really an optical illusion - it just looks like one!