Because my property is on septic and not sewer, such a heavy use (34 beds) triggered the County Environmental Health to get involved.

You can't charge for ESA's/Service animals UNLESS 1) the breed increases costs via your home insurance carrier or HOA (you can pass the increased cost difference down to your tenant, if they do not accept, you can deny); 2) the animals cause damage to the property; 3) The animal is a danger or is a health risk to other Tenants in the bldg. or to you if you live in the bldg. i.e. animal has bitten someone or allergies or animal is poisonous, etc.; 4) Animal size is too large to accommodate i.e. a horse, a 200lb. dog in a single room rental.  

It's not like I can just walk in their current place and see how meticulous they are about their pet's health and hygiene. 

Appraisal gap coverage and waiving all but health and safety issues on the inspection are other options if you're getting desperate.

The owner barely broke even - he was 80-something, in poor health, and didn't have the time or money to dedicate to the property. 

He has found no health or safety issues. 

I work 14 12 hour shifts a month at an urgent care dental clinic.

The other factor is insurance, and implementing an actual Health and Safety Program for your employees.

I obviously don't want them to leave, but I am also keenly concerned about their health, safety, and enjoyment of their new home.

The stock market dropped 28% over the course of half a year, they got tons of pushback from politicians who cared only about how things made them look and not the long-term health of the economy, and they were strong-armed into stupidly slashing rates again in 2019 even though inflation and unemployment were perfectly healthy, just to make the stock market look good as an election approached.