All I meant to say is that I understand it is a defect that is not evident on cursory examination, but as a consumer I would expect that if enough people complained to Kobo about it they would eventually see for themselves.
At the time I returned my Kobo I really could not figure out the rhyme or reason to when it would show up so I could not explain it to them either. There was nothing on the web about the defect last November so I just had my wife who also could see it to assure me I was not crazy. I just settled for the replacement with the same problem because I do like the device and I did not know what else to do about it.
Anyway the reflective crosshatching which is what I call it now definitely appears under halogen lights.
The other light in my house that seemed to cause it no matter what type of bulb I put in there was a floor lamp. Looking at it now I realize it may be because the shade has a silver backing. Halogen lights also have a silver backing in the bulb. I think this silver is definately the cause somehow.
The angle or intensity of the light is not really important. I have a dimmer on the halogen light and it does not help.
I do not notice it outside at all in my experience but it is winter and I was just holding it up to the window.