In a smaller city or town I could see that being dangerous, because they probably have only a few major employers, but Miami has a wide variety of employers so even a hit in one or two industries would not kill the city.

We bought this thing, rennoed it, worked out tails off, payed it off, got hitched, in four months he developed some sort of anger management disorder, we tried to treat if for a year, but the situation was getting dangerous, so it had to come to and end. 

This is dangerous for new investors who is working with an agent that does not understand the need to account for vacancy, repairs, maintenance, and property management fee. 

Highest return on investment, less dangerous than Hartford.

This is the most dangerous misconception.  

I also realized they are gone, have no money, have no character, usually have a substance problem and are not worth a lot of anger or fretting.  

Please advise me on the dangers of this.

It has almost no substance.

If they are in fact dealing drugs, they may be dangerous and I do not want them to know I know or I'm the owner. 

., but as all homes have to breathe a little (They have to or it would be dangerous to live there) wondering what limits there are.