Is it Possible to Pick Fly Shit out of Black Pepper?

The essense of the problem is one of detection.  There is a whole area of signal processing called SIGNAL DETECTION THEORY.  Its an interesting course.  I took it from Doug Cochran as ASU.

So how do you pick fly shit out of black pepper? You can not do it.  The joke infers that the 2 things are identical.  Being indentical they can not be discerned. So stop worrying.  You won't taste the difference.