You don't have to rent to anyone who is rude to you, or mean to their spouse in front of you, or whose children are out of control screaming up and down stairs, or who smell of pot or cigarettes or who appear high, etc., etc.You also can deny anyone who lies on an application or who doesn't complete it.  

If they smoke outside, the second-hand smoke drifts and the cigarette butts appear on the ground.

They mainly look for doors and windows that function and lock properly, appliances that work, that bath exhaust fans work (if no window) that you have functioning smoke and carbon monoxide detectors and secure railings if more than 3 stairs.There is more paperwork.  

While some of the suggestions above may pass muster on the federal side, your state fair housing laws may be much more restrictive.Here in MA, you had better treat everyone the same or there will be a smoking crater where your bank account used to be.We have state-employed "testers", who do things like apply for rentals.  

Emergency Contacts and Guidelines If something needs to be repaired or replaced:Please contact xxxx, LLC by sending a text message to xxxx at 303-xxx-xxxx.If you do not receive a timely response, please also try 303-xxx-xxxx.Fire, medical, or police emergency:If it is an emergency call 911.Please replace batteries in smoke and carbon monoxide detectors as needed and leave them and the fire extinguisher(s) in place.

I would attach a fine for each when it's not done.For item #2, I have had a house burn down because the tenant's kids where illegally smoking in the backyard.

So, when the courts open back up, they can also hear your arguments that you should be able to kick her out for the violations she didn't fix while everything was closed due to the virus - like having another tenant not on the lease, for smoking, whatever.

But, off the top of my head things that would probably be okay, that I'd want to add, would be a section about parking rules, how long guests can stay, smoking, no washing machines allowed, that kind of thing.

Your job is to not let them prioritize cigarettes or lottery tickets or pedicures or whatever over paying you.Next time, you won't let anyone slide. 

But, I believe you really need to talk to them in person, see their body language, do they smell like smoke, do they bring weird people with them to view the apartment, etc.