The laws used to be to prevent brothels from coming into towns, but they have since been used to prevent large living places like fraternities from popping up in quiet neighborhoods.

I own a duplex in St Cloud that I’ve rehabbed.https://www.biggerpockets.com/forums/522/topics/464525-investa-brothel-the-odyssey

It also doesn't know if there is a brothel across the street

We bought a 4plex (also our first) in UT that turned out to not be the "up and coming" neighborhood we thought, and soon after moving in learned that it was the town drug house and brothel! 

And yet all of a sudden there's this wildcard in the mix because the neighbor is using his home as a hotel, maybe even a brothel (I'm guessing some of you are fine with this - the founders approved...).Use common sense.This isn't a theoretical, or philosophical debate about what was intended, or should be.  

I've heard various sources say it was an anti brothel law, and others say it was anti fraternity housing in residential neighborhoods.

My questions to you are, Am I running a brothel?

@Bob Mastroianni Actually, the building was built in 1890, and in the 1920's, the upstairs was converted into a hotel (well, brothel).

Owning a place free and clear is as safe as you can get and you will be pretty much able to ride out most recessions, etc Fwiw I am reading two books that really helped me in my journey - “what every real estate investor needs to know about cash flow and 36 other key finacial measures” by Frank GalllinelliAnd “An Economist walks into a brothel” by Allison Schrager this is all about finacial risk and has been super helpful! 

Reminds me of the time I had to evict a brothel...