Jorabi wrote:
I own a 2-family house ... I live upstairs and rent out the
downstairs. I removed all the carpeting on my floor due to
allergies. My entire flat has hardwood floors that need
refinishing badly.

The problem is that noise travels too easily between floors.
Besides my footsteps and my/their entertainment/talking/sex
noises, my floor also squeaks and clicks a lot.

The second problem is that smells travel from the 1st floor up
to mine. They smoke and cook a lot.

I can't think of any options for quieting the noises ... I can't
get to the floor joists and I can't put screws through the
hardwood from above because I don't plan on covering it again
with carpet.

I also can't think of anything for the smells ... will sanding
and refinishing my floors stop them?

I used to own a 2 family house, only I lived downstairs and my tenant
lived upstairs which was carpeted. I still heard movement up there,
despite my tenant was a single woman.
You are greatly going to amplify your sound if you leave hardwood
floors.
And I don't think finishing the floors will stop the smell problem
either.