Most people I've known who actually got food out of the garbage knew which restaurants to go to and when; at close, pizza places throw out all their "mistake" pizzas, still boxed; 7-11 throws out tied trash bags of unsold donuts and pastries very early in the morning, when new ones arrive.
These were the kinds of things they'd get out of dumpsters.
The bulk of their nutrients came from free feedings, which were ubiquitous in the area at that time to cater to the homeless youth population, and from the food bank at a place called Project Phase.
I don't recall them ever eating anything maggot-ridden.
In fact, they were food snobs; some of them were vegans. Nearly all were vegetarians.
A couple of the most pragmatic referred to themselves as "Freegans"; they'd eat anything, as long as it was free.
The bastards would only wash with Dr. Bronner's soap, too. Project Phase started giving it out for free, because if Dr. Bronner's wasn't available, they simply wouldn't wash, and they were dirty and at risk for staph and other illnesses.