You may even need to hire someone to clean out the furnace and duct work to see if there are dead mice or other odor-causing problems.If they removed five dead mice, odds are there are more down there or the odor is in the dirt/wood.

I use THIS ONE and it works great on most odors (pet, cigarette, food).

The duplex in total is 2800 sqft (each unit is 1400 sqft)...Floors (Soaked in cat pee/poo): Repair (if possible-clean/seal/vinyl planks over top) $7,500, Replace: $15,000Roof (decent condition but looked like one soft 4'x4' soft spot): Repair: $750, Replace: $17,500Plaster Walls/Ceilings (like absorbed cat pee odor): Repair (multi-coat oil paint kilz): $2,500?

my tenants say there is strong odor coming out of the vents on the 2nd floor through the vents. 

however, due to strong odor, my tenants have temporarily found a hotel room to stay until the odor comes down. 

The sound and odor likely to come from the bathroom into the kitchen while you are eating is guaranteed to be unpleasant.

The odor can be stuck behind trim or in the subflooring.

They claim the odor was not present before signing the contract.

Not to mention easier to clean, and won’t pick up odors.

ESPECIALLY considering that you need to do smoke/odor mitigation throughout the same air compartment.