Yeah Marcus, my fingers might not be smart and tiny enough to fiddle with the polariser under the sunshade, let alone the risk of touching the glass and leave fingerprint.
Btw, what device are you referring to?

Oops! I meant the little wheel Giroud made to turn his polarizer. Sorry about that.

I think the risk of getting a fingerprint is enough to go to other means. A pencil eraser is a good suggestion, but I really do like the Cokin filter system or other matte-box setup as a more comprehensive solution.