But unless their businesses are structured very carefully they're no operating in the clear. 

Since you have bought a foreclosure before, at least you have experience with the liens and the process, but you won't get a final tally of the liens unless you can get your title company to run soft title search for these things in advance.Closing on a foreclosure anywhere in Brooklyn seems like a nightmare to me from an operational end.

But honestly, there are multiple (mostly all) operating illegally.

The main reason is other buyers who are better able to pin down operating costs will either outbid you because they have their costs right, or you'll outbid them because you have your costs wrong. 

There are also additional costs of operating and maintaining an LLC, like separate bank accounts, annual report filings, tax filings, etc.2.

This train is going to crash and there is going to be blood in the streets.

But we are testing this now.We operate 7 str's out of state...

I have a free training on my YouTube channel that teaches you how to create a comp set and review the competition in your market so that you can make an intelligent decision on whether or not to move forward.

I was thinking of doing Airbnb arbitrage in Cincinnati but discovered that there is a restriction that the STR operator has to live within 50 miles of the property.

It's finally a passive operation for me.