No it's never happened to me. However for those who do experience it I believe there initial distain for that person was (before) they ever really got to (know) them.
It's human nature to make a snap decision about which box to put people in after speaking with them momentarily or observing how they behaved under a particular set of circumstances.
Hypothetically you could despise someone you deem to be a "jerk" and overtime you discover their "back story" of pain and hurt and you come to realize their behavior is a (protection) device they use to prevent being hurt again or taken advantage of. Our personalities are shaped by our past experiences and the evolution of our understanding of how to best cope with the world.
In other instances we hate or dislike people because inwardly we envy them for being so "comfortable in their skin" and not appearing to care what others think of them. Our initial reaction is we think they are "cocky" or "self-centered" and we'd like to see them fail at something to "bring them back down to earth". Essentially we're envious of them on some level and wish we were as self-confident.
Last but not least there is some truth to the old cliché "opposites attract". We are oftentimes fascinated by others who think differently and behave differently than we do. When we are in our "dislike them mode" there is actually (sexual tension) or attraction underneath our hate/dislike. One day something is said or done that breaks the ice between you and your feelings start to change or reveal them self.