Definitely a focus area from lenders, conventional or otherwise - theres been a reported uptick in occupancy fraud or funny business lately as rates and values have continued to be so high and qualifying so tough - people are more likely to bend the rules on stuff like this - so this is generally the lender response

Or do you simply have to be obsessed to even have a chance to make it in this business?

Not a huge part of our business though. 

Could the argument be made that he had the experience because of the business he ran?...

Advise that the property has never been tagged by law or code enforcement as a drug production property and that their concerns are unfounded. 

A bit strange, I thought about this a bit and I didn't know if this could be signs of a sketchy scenario or if it was none of my business (besides the non-existent damage to the doors/ windows).

Recent Microsoft layoffs occurred in data centre operation business.

You are using as a single family residence (not business use).

Title companies often have a business development person that goes after real estate investors, offering foreclosure lists as an incentive.

You may get that in the STR/MTR space.The next thing to look at is the product and the markets; and that is where the rubber meets that road on these investment returns.