Today while playing I found an odd bush that was not completely revealed by my ward. A similar bush on the opposite side has the same behavior. My only guess as to why this happens is that the bush curves a small bit around the wall.
The admittedly very small section of the bush that has no vision is big enough to hide a champion or ward in, might be worth taking a look at. This is easiest to reproduce by warding over the wall.
This is entirely intended...you can use the corners to your advantage, or put your ward in a bad spot and be at a disadvantage.
Also, instead of using the Snipping Tool, you might prefer pressing Windows Key + Print Screen (copies only the active window) then pasting it into MS Paint.
That's kinda just the thing with line-of-sight and round walls where vision is obstructed beyond the point where the line hits the tangent of the wall. Happens in real life too.
Here are 2 images I made in mspaint to illustrate what is happening:
http://puu.sh/jHnVD/3199bab11e.png http://puu.sh/jHo0W/1893285c98.png
Notice how the the pink ball closer to the wall has a larger dead zone.
