He is securing expensive debt, not debt through a bank, isn't putting any capital into the deal and structuring the equity investment in a highly risky manner without any upside offered to the investor.

Active syndicators are frequently quoted in news articles or have entire articles written about them in trade and mainstream publications.

I've also used some more obscure companies in the seller financing world like Pioneer Title in Idaho (they call in Long Term Escrow Servicing) and Security Escrow in NM (recently purchased by Sunwest Escrow).

If they think they have an "Airbnb" Unless they own the publicly traded company, then they only have a STR, or a vacation rental if they have a nice place/location.

One that I'm getting close (hopefully) to the end of, was a flip that was a public nuisance property with two lots on either side full of junk (like 10 dumpsters worth..)There was great opportunity with the house, but we bought the other lots as well and cleaned them up (as no one would ever buy the house with those lots filled with junk). 

These are public records. 

But what is really important is that you understand the terms of the loan, including the length of time and when you can expect to get the money back, how it is secured, and the process of getting it back if things don't go as planned with the investment.

I know I need to hold the security deposit in an escrow account.  

Also, check out LoopNet or Crexi for listings, though keep in mind that the best opportunities might not be listed publicly.

Something of this magnitude would normally have a newspaper article, or a publicly accessible court docket.