I removed the Zagg InvisibleShield because the surface feels slightly tacky and when you try to scroll your finger doesn't glide across it smoothly.
Currently I'm using the screen protector that came with my SwitchEasy Colors case - much easier to apply or even to remove and reapply, and I gather that isn't the best screen protector but still much nicer than the Zagg.
I got dust under the InvisibleShield when applying it, and same with the SwitchEasy. The difference was that I could remove, wash, and reapply the SwitchEasy ones - whereas the InvisibleShield I gather once it's cured cannot be reapplied.