I have an ex pound dog who had no training but now she is perfectly behaved and her recall is about 95% (the other 5% is when she sees a friend arriving and has to go out to their car to greet them - then she is deaf to me).
I only found out how good her recall was by mistake. I was walking her and we were a few blocks from home and her collar snapped and she kept trotting beside me. She did this all the way home and when she saw another dog, a firm "Come!" from me and she just wagged her tail and didn't run off to greet the other dog. I had to be firm though in my sternest voice.
I let her off lead the other week to play with a red kelpie. They ran to the other end of the park but as soon as I said, "Millie, come!" and opened my arms, she ran as fast as her stumpy legs could take her back to me.
My friend can't do this with her spoilt little fluffy as she will just run off and up to other dogs bearing her teeth. Her dog is just a horror in that sense and she can't let her off leash anywhere. Last time she did, little fluffy ran up to a boxer and hung off its neck. The boxer thought it a game and chased her all the way home - the only time her recall was perfect :p