For example, I mention that every adult must pay a $30 application fee, pass my credit/criminal background, make a combined income of 3x the rent, and whether or not the property accepts pets.

While it may possible in older homes, water damage is still a concern and raises health concerns. 

Charge more to traveling health professionals.  

Consider all the things that could go wrong and see if the lease addresses them: unauthorized pets or tenants, early termination, security deposit, lease violations, late rent, eviction, lawn maintenance, parking, etc.5.

Are there dogs in the yard when you have a no-pet policy?

- are you going to allow pets?

Things like your vacations, entertainment, toys, food, clothes, housekeeping, pets, guns etc.

Quote from @Jerem Kaawaloa: I have spent the past 20 years working in health care and have only ever purchased properties for my own use, including a home and office.

We had many mishaps and health problems to deal with.

Things like your vacations, entertainment, toys, food, clothes, housekeeping, pets, guns etc.