The debt may not report to your personal credit (unless you are late on or miss payments, then all bets are off)2.

It sounds like you are missing a conversation with the tenant to understand the situation.

In my experience those that go alone often times don't end up closing any deals because it's information overload and they're drinking out of a fire hydrant and don't have any guidance to tell them what to focus on.

One or two little mistakes in your underwriting, a miss on the walkthrough, and you will blow right through your profit and come out in negative. 

Newark is a city where smart investors can do well, but uninformed investors can miss the mark.

And here in Chicago I always check my favorite local homicide tracker whose name violates usage restrictions.Is there other favorite metrics out there that I am missing? 

As an analogy to real estate… by starting of with a couple of smaller deals you will be on a much better footing to know more of the ins and outs of doing real estate deals so you aren’t a novice when you get to the 20 unit deal where if you miss something you don’t end up like the Tesla driver with lots of enthusiasm but not a lot of practical experience and you get burned.All the best!

Stop hanging out with your deadbeat buddies who spend all day drinking, talking sports, and otherwise wasting away.

If any of those are missing, well you've only got a 2 legged table and it's going to be issues. 

The new owner did not make the mortgage payments"I'm curious if I am misreading or missing some information, but I fail to see how your example supports what I take to be your stance.