Maintenance is deferred and most owners turned their units into rentals, hired property managers who did not care for tenant quality, which resulted in 10 people living in a unit, police coming over, drugs, etc and all the good people leaving.  

The next problem we are having is just trying to get ahold of him, he's a shady character who we are sure is a drug user of some sort and makes his living by stealing.

If the mother is using drugs around the children and ODed, they should remove the children from the home.

They left the unit in very bad shape (holes in walls, cigarette smoke smell, soiling and damage from unauthorized pets, graffiti and intentional damage, unflushed turd and vomit in the toilet, drug paraphernalia and liquor bottles, disgusting furniture and trash left behind, fridge, dishwasher and oven looked like crime scenes, cockroaches in the cabinets, grease down the drain, literally the works).

Tenants don't expect holiday gifts from their car dealer or the cable company, etc. 

If he is truly deranged or mentally unstable (possible with neat/bacteria-free issues)....you may be able to send a contractor (or multiple contractors) over to the crawlspace and leave some unpleasant smells, take pictures, and look for indications of illegal drugs.

No, we don't think you do drugs, but we will still tell you (and our police officer tenant) that any drug related crime on the premises will get you evicted. :-)We do have friends that we wouldn't rent to.

People who drink irresponsibly or do drugs usually have problems with fiances, credit, employment, and rental history.

We are the very good tenants -- no pets, no smoke, no drugs, no parties, very quiet, very clean!!  

I found out from the condo association office that the police has been out to the unit a few times on drug usage and charges have been filed.