In my experience the human eye can spot the lack of that kind of imperfections very well. Not quantify them - just notice that something is wrong. Regarding wa

In my experience the human eye can spot the lack of that kind of imperfections very well. Not quantify them - just notice that something is wrong. Regarding walls (and edges in general) not being perfectly straight, apart from what I learned from my engineering studies, I've done my fair share of home repairs :)