Algorithm to decide if you should recycle X:

    1) Is there a market for X?
    2) Do people steal X?
    3) Do people run successful businesses recycling X?
    4) Do street people root through garbage cans to collect and resell X?

If you can answer yes to 3 of the above, then you should recycle X.

I might have to fly out of LGA instead of JFK soon to try this out sometime.

Though, most phones have some sort of bluetooth capabilities nowadays. How bad of an idea would it be to transmit the boarding pass from the phone to the receiver that way instead of having to rely on the scanner?

Great, now you can fumble around with your phone trying to get them to scan it, then find somewhere to cram it so you can go through the metal detector.

but the black parts of a phone screen reflect as much light as the bright parts, so I don't see how this makes sense, unless we transition to optical bar code readers, which are much less reliable

I never thought reading barcodes from an LCD display would work, but some people are claiming success. I tried once at the airport with my iPhone but I had no luck in getting that thing to recognize the barcode. I'm guessing something like the Kindle should work pretty well though.