If she doesn't like going left and theres nothing physical, then lounge her on the left side ALOT horses think with both sides of there brains seperatly. And one side maybe okay to handle and the other might not. For example: A horse maybe afraid of whips so the trainer worked with her and rubbed her with the whip on the right side. And she was fine but when he went on the left side, she freeked. You have to work with BOTH sides.
I agree with horse_luver4e, horses are split brained. For example if your horse shys at something on the right hand side you should turn him/her/it around and give it a look with the left eye, if that makes sense....... Lunging is the same thing, horses are prone to like one side than the other.
Exactly, Maybe (if you haven't owned her her whole life) her previous owner might have only worked on lounging her on the right side and didn't change directions alot. And she was only worked with on the right side.