My first Go had a red pixel on the right eye - it was replaced(thankfully). The second Go has dust particles on the right eye....they are not as intrusive as the red pixel and i really only see them in bright areas, or one colored textures, but it it seems the Go really has problems with that.
I would sy that this is a no Go for an optical device, but yeah...i will not replace it again...who knows what issues the replacement unit has.
I would say, when it is in the middle of the screen, than try to return it as this gets really distracting and immersion breaking. This is nothing that you can fix by yourself, unless you have a Grade C Cleanroom in your basement 😉