And,,, after all, sunglasses are nothing more than a pair of lenses with coating on them.

As a retired DP, when you want polarization to change the properties of light as it relates to your eye (as in allowing only one plane of light to reflect in a window to see the reflection) it's one thing. There are a host of others. Color rendering was always the most important thing to me. The second was aberration . Funny, I'd almost without exception want a perfect lens, and then I'd stick a ten dollar piece of glass in front of it to change it, make it fuzzy or foggy or give it some other property the director desired.

The test you brought up is a good one. The second I would think (just off hand), would be to put a graphic (test pattern) at arms length and look at the image. Put the glasses on and see what happens. If you loose a lot of detail and you feel you're in a carnival, take it off. If it looks about the same (you may have to go outside when you put them on) then you've got something to go on.

lastly,, go out in the sun (they are sunglasses). Put them on and look at something in the shade with the sun fully hitting the glasses. Put your hand over the glasses making a sunshade. What happens to the detail in the shadows? Does it get clearer and have more contrast?, (probably), but what's except-able? If you don't see that much of a difference then the coatings are doing what they were designed to do. If the image radically changes then the coatings are junk!

Damn, I miss my job! (sorry, 4 beers)