Why do bats always turn left when exiting a cave?

Do they? Read on:

We can confirm that it is a common myth on the internet that bats turn left when leaving a cave. It has been observed that they have no preference and will turn right or fly directly ahead as often as they turn left. As you might be able to see. If you watch the video that we have on this page, it lays to rest the myth that bats always turn left when leaving a cave.
http://unrealfacts.com/bats-do-not-always-turn-left-when-leaving-a-cave/