I was spanked by my mother, but only if I had been really bad, and once I hit my teens I got privaleges removed instead.
My dad has the look, he still does, and that can still reduce me to tears! He never even raised his voice. My sister knows the same look, when she crashed her car at 22 she called me to get her and wanted me stood next to her when she told dad, it's a look of total disappointment and I could feel myself welling up even though it wasn't aimed at me!
My hubby was properly, belt removed and heated, spanked and from what I gather his dad was usually very angry when he did it. My hubby can get scary when he's angry, which I think is a result of this and also seeing his mother being beaten by his dad too. Though hubby would never hurt me or LO, he's very good at walking away when he's angry to avoid anything like this.
I don't think there is anything wrong with a slap on the hands to stop LO's touching something that could hurt them, but like someone else said, there is a difference between a slap and beating your kids, and I can see that from me and my hubby.