Why there is a black spot in the display of my iMac?
Gotcha! the black spot is actually dead pixels. I had an Apple Engineer to diagnose the display who said this is an obvious thing to happen and it doesn't happens because of daily usage. So I asked him why does this happens, he said that Apple has the tendency to reuse old and thrown out refurbished, recycled displays which is why sometimes these displays fitted into a brand new $1000 iMac shows these black spots/smudges specially in areas where the speakers are located!