Once you start hiring it out and passing around master keys, you can get in trouble if one of your maintenance guys gets on drugs or angry.  

It very much depends on your personal risk-threshold and definition of 'high crime'.For some people 'high crime' is when there's an occasional drug deal going on, for others it's 'drug deals on every corner'.

I've also found drug paraphernalia, kegs, and things on stuff on the walls from someone's nose.

I have chose to target these areas in order to avoid high crime- war zones. although, drug problems do exist, the local law enforcement seem to be watching closely.

As your portfolio grows, you will personally experience all of the horror stories: dealing with drug dealers; BIG damage done by tenants; lawsuits, evictions, etc.

They get involved in drugs, they drink, they don't pay their bills (including their portion of the rent), etc.

Additionally, many do not consume alcohol or drugs for religious or cultural reasons.The above boarding house is setup as a duplex with the "girls" upstairs and the "boys" downstairs.

If it's an open parking lot without gated access then criminals can loiter, deal drugs, etc. and make an easy escape.

Then there is a "Crime/Drug addendum", a "roommate" addendum, Pet addendum, and a few more similar addendums.  

Drug addicts in parks leave syringes on the ground, and it's unsafe for kids.