It reminds me of bitcoin when people wanted to get in way to late because it was jumping 600% a week and then all my friends who did it after me warning them lost their pants when it halved overnight. 

Warnings?

Any particular warning signs to look for when choosing a property?

Tell them what happened to you so they can put out a warning to their agents that someone is impersonating a commissioner. 

Your gut feeling could be trying to warn you.

and when I would NOT STOP warning people about this?

I wouldn't want to hurt my chances of renting out a house to people who like to drive by before inquiring, just to help people who are gullible and ignore the warnings on craigslist.I think one small sign by the front door might be helpful.When I was preparing to rent out my house in California and still lived there, several people came by and inquired about a deal on craigslist that seemed too good to be true.

All I am trying to do is give a warning.

I should have recognized that the repetitive closing throughout and,heightened approximately in the  last 30 minutes of their 2 hour pitch should have been a major warning signal but I ignored it.

But he warned me it's not fool proof, the seller can choose not to sell, and wait me out.