If outer space was a perfect vacuum, then there would be no planets or other objects occupying it. How much space are we talking about, and where is this space you refer to? for practical purposes, outer space is defined to as starting at a location past the Kármán line heading outwards from planet Earth. That does not however mean that it is a perfect vacuum. There are still particles, atoms, molecules and other stuff there.
I have also read that Astronauts detect the smell of slight traces of something burnt or burning. This can be caused by a physical effect to do with the way the brain reacts to certain conditions. It may not actually be due to the human olfactory system.
Even though such things may affect Astronauts, NASA or other space agency medical staff may not take it as a long term effect that cannot be corrected or stabilized. And as such still allow Astronauts to space walk with periods of recovery in between. Thus allowing the astronauts to effectively work in outer space, even though they experience such olfactory sensations.
Yeh, I also have seen that video with Astronaut Chris Hadfield. One of the biggest issues with Astronaut habitats in outer space is that they accumulate large amounts of dead skin cells. I mean, huge amounts! So if some of those dead skin cells deposited themselves on the space suits, and radiation outside the craft frazzled the cells, it would smell like burnt steak, when you come back inside the habitat/craft.