If it is routinely done it does not make sense to do it.

These laws prohibit discrimination based on race, color, national origin, religion, sex, familial status, disability, and other protected characteristics.2.

Winter/Harsh Environment/Disabled person/Vet??

Some of my best tenants in the 1/1's are older people on social security or people on disability. 

You can look them up for water and air.An interesting side note, if you superimpose a map of the U.S. showing cancer rates over a map showing radon levels, you will find no correlation.Testing has become routine during due diligence prior to a sale.  

I have routinely seen "$1500 carpet allowance with acceptable offer," on listings.  

 We started routine semi and quarterly inspections after a similar situation and it's been a great way to stay on top of things and build a better relationship with tenants.

I routinely runs quotes with most of the markets because there are often large differences between programs rates and which will be most competitive differs from property to property. 

If a service animal is removed for being a direct threat to others at a public place they must provide the person with a disability the option of returning without having the service animal on the premises.”https://whnt.com/2019/08/15/misrepresenting-a-pet-as-a-service-animal-will-soon-be-a-crime-in-alabama/

While anything is possible and a carpet cleaning job could potentially take multiple days to complete and involve large fan/towel/dehumidifiers, I would suspect it would be less probable it was just a routine carpet cleaning.