Paved roads are rarely flat; they usually slope in one direction to help water drain or to help a vehicle hold the road surface. The most common type of construction is the crown—a road higher in the center than the edges.
Since you lean a bike over when you turn, it’s important to pay attention to the crown. On right turns, the crown works for you, but on left turns it works against you. (This presumes that you ride on the right; in the UK, Japan and countries where you ride on the left, the opposite holds true.) If you drift over onto the crown, your machine loses its cornering clearance very quickly. And sometimes the crown won't be in the center of the road at all.