@Tony Velez, Good way to follow up.. try to source the area and ask tenant in #2 to try and limit smoking times and areas if possible that's causing the problems,, people with asthma and allergies are more sensitive and could get a doctors note saying they can no longer live in unit due to second hand smoke and you'd be hard pressed to hold them to their lease if you can't solve the issue. 

The reason was that they were young doctors from another country doing a fellowship program in the United States.

I'm not a doctor but I did stay at a Holiday Inn Express last night.I work with these issues exclusively.

There was also significant population growth and job growth was fueled by tourism (every job is Las Vegas is fueled by tourism, because without it they wouldn't need construction workers, teachers, doctors, etc).

Clineeds has several listings also that are from hospital systems, directly marketing to doctors.  

While financials are often doctored to make them better than they appear you at least have a starting point.

Doctors are "rich people" often times protected behind legal processes like insurance. 

I've got a potential tenant that has a companion dog (with a doctor's note), not a service dog.  

This sounds like something a doctor or other independently wealthy person might do, to leave to his children as investments. 

I have a service animal request form that requires, among other basics:Written statement from doctor or qualified professional.Appropriate current State, county and/or city licenses.Evidence of current vaccinations from local veterinarian.