They could have been DUIs, does this make him a bad tenant, not necessarily but he could get fired tomorrow for wrecking his company car and refusing a breathalyzer on the scene.

Ask them to breathe into a breathalyzer when you do the showings . 

BLOZF aka Cannabix Technologies is developing a breathalyzer that can measure it on your breath instead of taking urine or saliva samples.

You don't stop every driver on the road and administer a breathalyzer just because 2% of the drivers may be drunk at any given time.

I had animal control after them for a dog that barked in the middle of the night and when the tenants' brother got drunk and wrecked their car I called the police and told them to give him a breathalyzer and when they showed up and he failed the sobriety test they took him to jail.Most people fear confrontation.

The car has a interlock (breathalyzer).

Self-inflicted because I only had 2 beers, stupidly refused the breathalyzer not knowing if you do that, you automatically get the highest tier DUI.