Yeah I had trouble with my screen protector as well. Looked to be good, and then an errant piece of dust landed on the inside and I wasn't able to clean it off. At least it was free.
I think the wet application screen protectors work better but I usually don't even bother with them anymore, too messy and too many bubbles and I hate the idea of spending the money for one only to screw up the installation. On top of that, I never know if I want to buy a cheap one (potentially waste less money) or an expensive one (get what you pay for).