Ah so thats burn in.Sorry but I never really saw it on any AMOLED displays I own till now.More to the point,one defective screen does not mean all S6 Edge suffer from it.FYI,I personally encountered a different type of issues with Apple's LCD.You know,the infamous yellow tint issue which is over a 100 pages on macrumors for both the 6 and the 6s and keeps popping up every time a new iPhone is released.Let me tell you,it took nearly 5 tries for my iPhone 6 and 2 for my Air 2 before I won the screen lottery
This does not mean all 6 suffer from this issue but also proves that Apple's LCDs also have similar problems.Thing is burn in problems are lesser in number than YELLOW TINT on an LCD.Another reasons why AMOLEDs are superior.The white is more even than on an LCD