On these chair by Sanaa, the chrome has a subtle white cloudy appearance. What would be the best way to achieve this? I don’t think it’s a result of roughness, but could be wrong.
looks like marks/smudges on the top surface - so a clearcoat layer with imperfections is probably needed
Corona physical material has base tail parameter. Try to use it. It’s also mapable if you need to brake the “cloudiness”. Just remember, subtlety is the key here.
A +1 for the base tail parameter, giving metals that “depth” and “bloom / glow in the reflections” is what it does well 
+1 for Base Tail
-1 for not explaining what it is and where to find it 
Here: https://support.chaos.com/hc/en-us/articles/4954436712337-What-is-the-Base-Tail-3ds-Max
You can map it with a texture and you will get a result very similar to the reference photo.
Thank you everyone. ‘Base tail’ was what I was looking for but is a bit hidden as far as features within the Physical Material options.