Outside of one or two incidents, my parents were able to abstain from hitting me as a child. I still turned out pretty well. There's no rel proof that spanking, or any form of corporal punishment, works but there's a lot of evidence out there that it may well have a detrimental effect.
Back when I was going for my master's in education, I recall one professor, who specialized in students with disabilities, talking to us about calling home when a student was not doing well academically. He said that he always avoided doing it because a large number of parents' first reaction was to smack the kid around a little. He was an older guy so I like to think that it's decreased since he was in that position but hearing that was pretty sobering.