Thought I would post an interesting observation... This weekend I broke the frame on my regular prescription glasses that I wear when I use my dark smoke shield on my Shoei helmet. I was sweating so much my glasses started dropping down my nose so I brilliantly used some needle nose pliers to bend my wire framed glasses in a bit to make them tighter and spoof...snapped the frame right in two. Luckily...I had some backup prescription sunglasses that are polarized so I switched to my clear shield, put on my prescription sunglasses and went out next session. Wow! Talk about a different view...could clearly see how blue (ieily) the tar strips are and how clear the race line is. Off the race line the track was much more blue than the race line, but the tar strips had many ziggly lines and a rich blue. Pretty amazing I thought. Coming up the hill to Charlotte's Web and up the hill after the museum turn with the sun past it's azimuth (I think it was the 2:40 Novice session) the effects were most clearly visible. Lol..might be good to use on first session just to see where the most slippery parts of the track might be! Just thought I would share...
There's something else to get in my head LOL. I can't function (I can but don't like it) in bright sunlinght without quality polarized sunglasses. Good quality lenses can make a huge difference. They completely cut glare, and sharpen contrast greatly, as the OP noted. You see things you can't see with naked eyes, or cheap lenses. Good quality polarized lenses even help on cloudy days. There's still sun glare on cloudy days, and good lenses helping with contrast actually seem to brighten, where as a cheap "dark filter" lenses just make things darker, and thus hamper vision all around.
On the track it generally is not a concern as the corner workers will toss a debris flag on oil fast (and generally a red from the few times I have seen).