Yes and no. My parents slapped me occasionally, it didn't hurt and it sas for the wrong reasons. Such as i turned around and couldn't see my mum so got upset and got a smack. Nothing hard or anything, now of a tap but quickly learnt to not give hoot where my mum was ever again. 
When I was much younger I also saw this lady in a charity shop really slap her child hard on her back cos she'd picked up a toy. I didn't know what to do myself at the time. It's stayed with me.
I don't have kids (ttc) and I don't intend on ever hitting my children. But I guess never say never depending on circumstance... I think It'd have to be extreme. Such as if they were about to run into a busy road or if they behaved in a particularly bad way though I'm not sure what that would be. And hopefully they wouldn't do it in the first place if I bring them up correctly!
I watched a documentary on YouTube about a parent who believed in smacking. The kids were just being kids and the smack was probably not painful, but obviously it's the action. If you give your wrist a light slap on the wrist it doesn't hurt does it?
It didn't seem to do any good though. The kid cried but the behaviour came back the next day. They still did a lot of nice positive things with them and praised them for good behaviour. And got time out and an explanation as to why etc. They said they probably have their kids at least one smack each a week.
I doubt it would really have huge negative effects on that child, although obviously the slapping works probably no better than the non slapping method, I thought they were really missing the point. Maybe these kids grow up with a fraction less trust in their parents. Maybe just enough to never feel that close to their parents. Or who knows.
I don't think their choice made a positive difference so what is the point?
99.9% against.