First of all, take into account the size of the locations. In this case, the Kages are fighting at VoTE, but against Orochimaru, he was fighting on a small rooftop. Obviously, the enclosed rooftop is a rather small space [
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], so smelling Hashirama and Tobirama is entirely possible, as they're not too far away from one another. VoTE is a large area [
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], so tracking the Nidaime is going to be a lot more difficult. Not to mention, Hashirama and Tobirama have been dead for years, so obviously being dead bodies and all, they're going to... stink. Smelling the clam and Mizukage? Not likely. To be honest, I never even knew clams had a scent, but whatever. Hiruzen is going to be constantly seeing Mirages [
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], so he won't know where to attack. In any case, Jouki ends him. Hiruzen lacks the means to hurt him, and Jouki's speed turns Hiruzen to nothing but limbs.