I find that if I wear a light shirt I cannot easily read the screen of my glide computer because it is mostly washed out by the glare off my shirt. This is worst when I have the glide computer on my kneeboard (in club aircraft) where its face is more often perpendicular to the sun, but is also a problem n my glider, where I have a permanent mount in a position that isn't directly in the sun often. (I've never had success with temporary suction cup mounts).

The problem isn't really so much that the sun is directly on the instrument, it is that the sun is directly on the shirt! This gives a massive reflection on the computer, on the instrument panel, and on the canopy, all of which I find distracting.

When I wear a dark shirt all of these issues are greatly reduced.

Van