It appears that label rotation on charts will rotate on the label's center point. If you have long labels for a column chart, then a rotation of "35" would cause labels to start at the wrong spot, and it pretty much unusable in that state. The start of the label should be directly below the chart point in this case. Maybe there should be a way to specify the rotation point on the label...something similar to "start", "middle", "end". In my example, if I could tell it to rotate 35 degrees from the beginning of the label, it would render correctly.