I think I've discovered a way to atleast sort high grade boards from low grade boards... (I'm sure I'm not the first to notice this)...Please correct me if I'm wrong.

High grade boards are quite a bit more difficult to snap in half with your hands
Low grade boards are "brittle" and snap in half very easily.



I was wondering why the flat screen TV boards were so difficult to snap in half...So I tried some boards from a recent PC and they too had the same difficulty.

But a board from a CRT snapped in half very easily.