I found that if I waved too close, it wouldn't work. It specifies 6" from the front of the phone. Most people will tend to swipe about 3" away or about the width of a hand. So for greater reliability wave about two hand-widths away, and adjust accordingly.
I am not saying you will definitely have problems with a screen protector that covers those IR emitters, but it will have some impact to the amount of IR light that gets transmitted, no matter how little it really does reduce it by. If it's a 5% reduction, you might find that 6" is too far away and you have to wave from closer, like 5.5". to most we're not going to get a ruler out and check, we'll just adjust our wave till it works.
Regarding the actual sensor at the top, there were Droid RAZRs and RAZR MAXXs that came with a plastic screen protector just like the one that came on the Turbo. Just like
@iiWoodstocK , I kept that one on my MAXX, and like him I rubbed the white text off. Initially I didn't think I was having any problems with the screen protector in place but it didn't have a cutout over the proximity sensor (next to the front camera), and what I found eventually is that the feature that shuts off the screen when you bring the phone to your face wasn't working correctly. Sometimes it would stay on, other times, it would go off but wouldn't come back on when I brought the phone away from my face.
There were others experiencing the same issue. It was eventually determined, I think it might have been
@94lt1 who figured it out, that the screen protector was the culprit. Sure enough, removed the screen protector and I never had an issue with it again. So it all depends on what frequency or wavelength of light is passing through the screen protector and what frequencies of light it might naturally attenuate.
Since IR is invisible to the human eye, looking at glass that completely blocks IR, we see nothing but clear glass. This type of glass is commonly used for window glass in houses and other buildings (most commonly in the South) to reduce the amount of heat that penetrates the building and reduces the efficiency of the air conditioning. The same holds true for UV light. So if the glass looks clear to our eyes, that doesn't mean it is in all wavelengths of light. It might block significant light in any of a number of wavelengths, both visible and invisible to the human eye. Of course, if it blocks a specific visible color or wavelength of light, the glass will appear tinted in the opposing color. In other words glass that blocks blue light will appear orange/red;
and red blocking glass will appear blue/green.
Infrared blocking glass appears clear or slightly gray;
And UV blocking also appears clear;