It is a big part of why our team is able to analyze and acquire properties anywhere in the country, and I suspect will take you far in the future as well. 

If I suspect a flop/meth house and its always very apparent its a no brainier...leave it and don't bid. mitigating meth will break anyone.

I suspect Zillow or eRentpayment or many other ACH based payment systems work about the same. 

Otherwise, I suspect they get hammered as much as us with people asking for our business.

We are under contract for a house that I suspect has asbestos popcorn ceilings.

The seller gave me his inspection report from 4 years ago when he bought it, and the inspector suspected asbestos floor tiles in the entryway.

Then YOU hire a licensed, insured, professional contractor to make the improvements so your tenant is safe.I suspect the tenant is renting below market which is why he's willing to put up with a substandard living arrangement.

One if you default its a nightmare for them.. plus they probably cant buy anything else with that mortgage on their fico.. if they ( seller ) get advice from any real estate professional I suspect that advice would be to not deed the property over unless they got a SUBSTANTIAL amount of cash out of you then maybe its worth their downside risk.  

Any potential illegal activity that they suspect should not only be reported to you, but they should file reports with the local police.

You said it was C- area but I suspect its D or F, based on the gross rent.