Every clue is not a lead.

"Every clue is not a lead."

This line says that the set of all clues does not include as a subset nor as an intersecting set those things which belong to the set of leads.

This is patently not true. The set of a clues does indeed intersect with the set of all leads. There are some leads in the set of all leads which are not included in the set of all clues.

The sentence should read, "Not every clue is a lead." This sentence isn't even less dramatic or less intelligent than the original. The original is just dumb but so many Americans are guilty of this kind of wording.

"Bob, you have to understand, you can't paint your living room pink. Everyone doesn't like pink." They mean that there are a lot of people who don't like pink, but they have said that every person doesn't like pink. There is nothing wrong with saying it correctly, "not everyone likes pink." It's even the same number of words.