This is true. And the best way to avoid it is leave the tawny and the homeless to do their own thing. Avoid dark parts of town. In general leave the violent multi-hued tapestry of diversity to the colored people. They bought it. They own it.
I was in San Diego about 12 or 15 years ago for a corporate event. We were staying at a high end historic hotel, the US Grant, in the Gaslamp District, a tony restaurant and hotel area.
Even back then, all the pocket parks were filled with urban outdoorsmen on most of the benches. I was amazed the city would allow this, night and day, in this area that was supposedly the best the city had to offer.
This slide has been developing over a long time, it stems from a long period of inaction on the problems these addicts and mentally ill cause.