Good dropouts are also moulded rather than stamped so look for some curvy detailing. Even if the tube labels have worn off, dropouts are a sure sign of bike quality.
Bike frames tend to fail in non-critical parts such as the drive-side chainstay. It is rare for a steel bike to fail catastrophically and dump the rider. You just notice a noodly feeling and behold, your chainstay is waving in the wind.