Smells are typically transmitted by vapors (gases), which lack the intermolecular forces that are responsible for cohesion, and cause water and other similar liquids to gather into droplets in zero-g environments. What would happen is that the gas responsible for the smell would diffuse away from the object equally in all directions.

I'm actually not sure how true it is that smells are stronger above an object than below it on Earth. It's hard to smell a mug of coffee from below because it isn't open at the bottom, for obvious reasons. And our nostrils are on the underside of our nose, so it might be a bit harder to smell scents coming from above our nose. However, if I held a piece of stinky cheese above my head and turned my nose up to sniff it, I'm pretty sure I could.

Edit: on large scales, gases do indeed gather into nebulae and sometimes even gas giants or stars (or solar systems or galaxies), but this is due to gravity rather than cohesion, and to be a significant force this requires much much more mass than the tiny amount of scent molecules that one would find radiating from an object that would fit in the ISS.