There are many red flags here, that can be ignored.

Could be a red flag if they don't. 

Debt aside, there are a few red flags with the rental like its close proximity to high crime apartments and a recent garage break in.

I just finished the design / construction management of 45 low-income units here in Redding, Ca at a cost of $222k per door.

This is seasonal and easily removable Red Devil 0606 Zip-A-Way

We took some of that money and bought 100 acres with water rights and a lake off Red Prairie (between Sheridan and Dallas OR). 

That being said, the code enforcement or city inspectors will Red tag a project if it is not being done correct.

There are significant costs, time, and red tape involved.

The video with ten red flags you talk about people that want to plant gardens or flowers being a red flag.

I remember having a brick fireplace painted and they painted it bright red, very odd looking, our normal spec was grey but we didn't do a full scope as it was just a minor rehab, paint and carpet.