Denying Applicants or Prospective Applicants from Applying?

[Donovan Carson]

Hello, 

Ran into an interesting situation tonight and wanted some advice on what to do - I appreciate your time and thoughts in advance. 

Currently marketing a unit for June 1 that is a one side of a duplex. It's posted for $2200 and I have my standard credit, background, and income-rent criteria.

I showed the unit tonight and everything about the showing gave me the gut feeling of "don't rent to these people." They (3 roommates) showed up clearly high and smelled like weed and slurring their words. One of the high people commented on the way out the door "these stairs seem dangerous like someone might trip and hurt themselves." The stairs are perfectly in tact and safe with no obvious issues, they were just having a little trouble putting their shoes on in the split entry without falling over because they were high. Someone mentioning that, to a landlord nonetheless, would lead me to think they might be frivolous.

They are interested in the unit and want to apply and I currently don't have any other applications in right now. I'm afraid that in the application they may pass all the "criteria" pieces but I still know it is not a good fit. I feel as though renting to them would be a mistake but I want to legally and rightfully deny them. 

How would you proceed?