Look closely at the application. You can always find some other reason to deny them. Here is a list.
1. not enough income 2. not enough work experience 3. no landlord references for last three residences 4. not enough rental experience 5. Credit score under 700 or more if you set it higher
Is this applicant disabled. Is this a dog that performs a service for a disabled person or a "therapy animal" that is just another way of sneaking in a pet. When did America get to the point to where a significant part of the population has to get through the day by hugging a "therapy animal."