Well... I have applied dozens of screen protectors... and that's true, it is hard to get a dust free environment... but I am sure they are not sealing devices on their home with a garden
I agree that almost all devices have some particle under the screen, but I refer to those that affects 1+ pixel.
If your device has a dead pixel... do you keep it or do you try to get a replacement? And what if it has 2-3 dead pixels? Because sometimes, dust under the screen has the same effect as dead pixels.
This I can understand, didn't realize it was that bad as some iTouch's I had awhile ago had lint under them but it was very minute, and basically invisible unless the device was off.