Lefties Only Golf Tip: As with any golf club, a putter has a sweet spot. It's an area in the center of the club, around about the size of a small coin where the ball will feel its best when you hit from there. It will also roll the straightest and roll the consistent distance that you're used to seeing. Any ball that's hit around that sweet spot, on the outside of the sweet spot, towards the toe or the heel with top or the bottom, would start to react a bit differently and feel a bit differently.
Left Hand Golf Tip: Hitting the Sweet Spot Crucial to Good Putting (Video)