I know in my area there are several hotels that were shut down by the city for basically being drug/prostitution nexuses.

Riff Raff, whiskey, gambling, prostitutes, con artists, and other shady characters run gamut when the refinery is doing major work.

I've dealt with pimps, prostitutes, drug overdoses, venomous pet snakes, theft of service, dead bodies, break ins, walking in on an intruder, etc. 

The son got locked up 3 month ago and the prostitute found another sucker to house her .

For example, I post my problems with prostitutes in my STRs in a duck hunting forum. 

Yes, sometimes those go hand in hand, but if you stay out of the drug house / prostitution hoods you can usually avoid the violent stuff.SCREENING: Yes, be sure to pull Credit and Background. 

What type of business do they run... prostitution, drug trafficking? 

The plan now may be waiting on market changes building nicer homes than originally proposed.Lots of assumptions can be made.Best way to learn in the developing arena is 1. get with a developer and prostitute yourself with labor to hang around and learn or 2. do the same with a civil engineer that is active in developments.

What if the business is illegal and is just cash, like drugs, prostitution or gambling?

you know we had the craigslist killer in Boston, set up appointments with prostitutes and killed them,,,do we have a Bigger Pockets stalker,,asking for a mentor then holding them hostage until they tell all of the 'secrets of real estate".....I bet he is on vacation or busy with work