A mousepad won't make your trackball roll smoother.

No, the surface doesn’t matter for how the ball rotates. A trackball’s ball spins on bearings inside the housing—it never touches your desk. The desk only supports the device.

If your desk is perfectly flat, a bare surface works fine. Where a mousepad might help is if your desk is uneven or slippery, just to stop the trackball from sliding around while you use it. But for ball smoothness? Zero difference.

Some people worry about dust or dirt getting into the bearings, but that comes from your hand and the environment, not the desk surface. Keep the ball clean and you’re good.

Don’t overthink it.