You'll never know everything and you'll learn the best from personal experience but I do recommend knowing enough to be dangerous before jumping in with both feet.

Real estate although alluring with it's profit potential can be dangerous when not executed correctly.

I've browsed and searched the forums but i typically find guides on how to become one, not the concerns/dangers of dealing with one.

Environmental companies can perform an assessment called and ESA or "Desktop Review" its a historical record search that ties into a number of databases that will know the history of that tank if their is one, who put it in, and if it is still deemed "hazardous or dangerous" to the public.My company is an environmental firm that handles these types of issues in the commercial and residential real estate industry.

Right now, you're dangerous - to him, to yourself and to your clients. 

When you don't pay them rent it can be physically dangerous (allegedly).

Simply looking at financials is frivolous and dangerous and such recommendations threaten the longevity of his wealth. 

Do a quick search of "newburgh ny crime", in 2015 it made the top 10 most dangerous cities in America...looks like it's improved a bit since then.  

Yeah, @Ashish Acharya ventured into those tax planning strategies I vaguely referred to.Slightly dangerous without a thorough discussion, which is why I stopped at the door.

Our rental is in the Tower Grove east neighborhood, which seems to be right on the edge of trendy and dangerous (aka cheap but rising fast...tons of buying, selling, and flipping in the area).