I have yet to come across a GPS mapping app that can avoid the nasty areas in cities or towns.
Because of the options: fastest, shortest or most fuel efficient the app doesn't care where it routes you and I have landed up in some really dangerous places in Africa because of this.
For the reason above I always have a paper map alongside me to keep the GPS honest and to get a broader overview of where I am. Paper maps will not be of help in avoiding nasty areas but they will at least show you when you're being routed off the main roads.
On a lighter note - T4A routed me via the sewage farm in the very rural little town of Tarkastad once. That was the shortest route 😂