There absolutely is a standard. Its to not polarize aircraft instruments so they conflict with Polaroid sunglasses--which are all polarized in the same direction to cut down on reflection off water/road surfaces etc. Cambridge simply (years ago) had a batch of 302s where the glass was installed incorrectly.

There is maybe less of a practical standard for handheld devices becuase some devices are intended to use in portrait or landscape orientations. Manufacturers need to make a best guess as to which orientation is more important for users wearing polarized sunglasses. If the device is only designed to be oriented one way then the choice for them should be obvious.

Polaroid sunglasses can have significant benefits to glider pilots, including making haze dome/wisps more visible (darkening the background sky and maybe direct polarizing effects) and making gliders more visible against darker sky. This is further enhanced if the sunglasses are strong "blue blockers". Besides difficulty reading some PDA/PNA etc. screens polarized sunglasses may show stress patters in canopies. I've flown in quite a few Mecaplex canopied aircraft with Polarized sunglasses and have had no problem at all with this. The side windows on my Toyota Tundra show more patterning.

As a final note some cheaper polarized sunglasses may suffer from poor aliment of the polarizers, so you'll see different darkening in each eye as you rotate say an PDA/PNA screen or even look at different parts of the sky.

Darryl