Does the gloss level of a mouse pad affect sensor performance?

Yes, the gloss level matters — but mostly for older sensors like the PixArt 3360. Newer generation sensors (3395, 3950, etc.) handle glossy surfaces far better. The 3360 can get confused by reflections on glossy hard plastic pads, causing tracking skips or jitter, so a matte pad is safer. With a modern sensor, you can use whatever glossy plastic pad you like.