To sum it up, bump steer is anything that changes the direction of the front tires other than rider input. Like, hitting a pothole or rut and your tires jamming to the left or right...
Typically, you want the center of your wheel, centered over the ball joints of the steering knuckle. Wheel spacers will push the centerline of the wheel far from there and give you some bad bumpsteer, I would NOT recommend it for the front. You can help control bump steer with a steering stabilizer, like Noss Machine sells. I have that exact one and it helps. Another way to eliminate is to move the wheel centerline, like using 4-1 offset wheels, this makes bumpsteer a thing of the past, but it narrows you up an inch on each side, so most peeps won't run it. 3-2 is stock and you shouldn't have problems at that offset. Flipping wheels or using a wider offset can give you problems.