For the apartment unit, the urine went through the laminate floors in the entire apartment and even after we removed all the floors and painted them the urine still smelled.We had another apartment where the dog odor was so bad we washed all the walls and ceilings, painted them, took all the lights, switches, wall receptacle and even took the furnace out.

Start by having a respectful conversation with them about the odor and suggest solutions like designated smoking areas or air filtration devices.

If the place is vacated with significant lingering odors, that's one thing - but anybody can be smelly.

You could easily have a major Special Assessment just around the corner which will foul all of your planning.

Hotel and motel owners (and other small companies) save a lot more, because they have such large portfolios with a LOT of write-offs. some of your properties may not offer a lot in savings- but if they don't, they will tell you it's not worth doing- no harm, no foul.

If it's not allowed/additional question, would converting the garage to expand living space potentially run foul of the parking space requirement (or is there an exception for that now too like there is for converting garages for ADU's)?

They absorb pet odors. 

When I came back, the cat urine odor was no less bearable.

No odor at all.  

No harm no foul.