I've had to work on a few glossy screens and the old CRT monitors were glossy anyway. I never managed to comfortably focus through the reflections. Even on out flat screen TV, I can see reflections when it is sunny outside and I end up watching the reflections, not what is being shown. Some brains might be able to filter out the effect, but mine focuses on the effect.
I have the same problem with background sound, I cannot filter it out and if somebody talks to me in a room with background music or conversation, I'll probably only hear a third of what they are trying to say. It is even worse when they are speaking German.