There are any number of reasons to prefer one rental applicant over another. For instance, you may have two qualified applicants, each with good credit, but prefer the candidate who is a non-smoker.
At the same time, there are some prospective renters with flaws that are so fundamental, a landlord simply can’t afford to give them a chance. If you see candidates on this list, it may be cost effective to turn them away:

1. Violent crimes.

The propensity to commit a violent crime puts other tenants and neighbors at risk, and increases the landlord’s chances of getting sued for negligence. Once word gets out that someone who could be dangerous is living nearby, the whole neighborhood will be up in arms about it, and other tenants may leave.

2. A prior eviction.

A prior eviction speaks volumes about a tenant. The fact that they broke the rules, like failing to pay rent or ignoring the lease, is bad enough. But not owning up to it, and making a landlord spend countless hours and dollars to pursue an eviction case, and ultimately force the tenant is out is even worse.

3. Incomplete application.

When you see a lot of blank spaces in the app, chances are high this applicant is hiding something they don’t want you to know. Maybe they are hoping you won’t notice. But you need that information to get the most from your tenant screening reports. They didn’t waste any time filling out the application, so don’t waste any time in rejecting them.

4. Can’t produce a landlord reference.

An applicant who asks you not to talk to the current landlord is a high risk. This is someone who may be breaking their current lease, or trying to get a new place before the eviction goes on record. If they are doing that to their current landlord, there’s no reason to believe they won’t do the same thing to you.

5. No verifiable source of income.

Illegal marijuana grow operations or other crimes are commonly conducted in rental properties, often in very nice neighborhoods. These properties suffer significant damage, become vacant crime scenes, and may be treated as environmental hazards, requiring an expensive, government-supervised cleaning. There may be no criminal report on the applicant, at lease not yet. But running a tenant credit check and seeing no employment listed can tip you off. Applicants who are self-employed or cash-only business owners need to be scrutinized.