we can now conclude tht madara or tobi have nothing to do with zetsu.
if zetsu was part of madara then naruto would of been able to sense madara too since he can find the zetsu clones so easilyy
Naruto can sense evil intentions that's why he can sense the White Zetsus. Why does Madara need to be detected by Naruto? No where in the manga does it say he can't be detected through normal means.