As with most things poker-realted, one subject can have several answers.
Firstly position, then cost of calling,
Is it worth it,
Can you afford to lose your the amount your calling ?
Is your oppo short-stacked (therefore maybe desparate),
How loose has your oppo been playing? (maybe bluffing
to pick up the blinds)
how early in the tourney is it? (you dont want to bust out too soon),
has the dealer tipped you the wink, lol
Does it feel right?
Also remember AK may called 'Big Slick' but even a pair of 2's can beat you if you miss the board.
So once you have the right kind of answers covered, then you have to face the cards themselves
Sometimes it will work, othertimes you will walk