So, this is going to sound super nuts to some people, BUT... I'm actually considering buying a (2nd) property that is right smack in the center of Bloods territory. I am doing some research, and therefore came across your post (albeit a number of years later) so I thought I'd comment my experience....
Very long story short as possible; as newbie lenders back in 2019 we lended to a flipper out of Columbus who obtained by wholesale a 4BR house close to downtown and within a short walk of Nationwide Children's Hospital in an area which is going through much gentrification. The flipper, also a newbie it turns out, was so sure he was going to make a fortune off of the sale of the house with little effort, frivolously spent the money we loaned him to flip and ended up underwater and unable to sell the house for his asking price. We then acquired the house under deed in lieu and finished the remodel. Still unable to sell the house for what what we had into it, we decided to see what we could get for rent. We ended up renting to a lovely, two income couple with three small children (she works days, he works nights) who actually came from an even worse neighborhood and were grateful for the opportunity to move to a larger house in a "nicer" area. It took almost a year later and a very scary incident in which a stray bullet from a nearby shooting ended up going through the house and entered in a wall just behind our tenant's daughter's head while she sat on the couch to realize that the house was right smack in the center of Bloods territory. Had we known this from the start, we NEVER would have had ANYTHING to do with this property and would have run fast and never looked back. The couple it turns out were fully aware of the gang presence. And we learned there's even a website you can go to find out where their territories exist. It's now over a year since that incident, the rent we charge is significantly lower than nearby comps. The home equity has increased by $100K. The family is still living there, now on a month to month tenancy since our one year lease expired. They they are good people, take good care of the house, and pay their rent on time every single month. The gang members know who is, and isn't a threat and they do not bother them. The hope is of course that with gentrification, eventually (likely a number of years still down the road) the gang members will trickle out and find someplace else to do their dirty work (or even more hopeful—disappear off the face of the earth) so that decent, law-abiding, tax-(and rent) paying people can go on living their lives in peace.
Circling back to your question @Yishi Garrard, although it seams the realtors/property managers and even flippers ought to know what's going on in those areas, I am not convinced they do for the most part. A few handymen we have hired to go there do know what's going on. Some of them even carry to protect themselves. It's a mad world we live in whether we're aware or not. And very often the fringe and the fray as @Al Williamson so eloquently defined, have much overlap. You see this mostly in large cities, where one street there is much wealth and the next street, or even down the street/across the street there is deep poverty.