As others have said, use Google Maps. I use the basic view to get a general look at the streets from the sky, they zoom down to street level if I think there's anything 'odd', to see the shoulder width, road surface type, odd-looking intersections, trashy roads, bad neighborhoods, etc. Works quiet well to locate problem areas so you can choose an alternate route if possible. It doesn't work all the time, but it does help you locate the majority of the spots you want to avoid.