I've read some articles by magicians (derren browns books too) where they say most of the trick takes place in the spectators mind AFTER the trick. ie they saw him lift a pack of cards, and later in their mind the story becomes that he opened a new pack of cards.
Apparently it's how our minds work, we will tell ourselves that it happened differently in order to justify not checking it at the time.
Just as an example Bahco, thinking about it now, you probably would've turned the light on and walked round the table. but you didn't at the time.
In hindsight you may tell yourself that you could clearly see the edges of the table so there was no need to turn the light on.
Then a trick where an assistant was hiding at the edge has just become even better because the spectator assures us he could see all around the table.