Well... there are certain times when you should spank them. Not abuse them but just spank them if they are being stubborn or bad.
There are other ways to earn your child respect so you shouldn't only go for the smacking.
I also think that sometimes and this is a matter of opinion but at times your child can have a strong temper where it is almost impossible to get them to do what they are suppose to and that's when I think spanking them helps.
I was raised with spankings and smacking here and there and I don't think my parents abused me whatsoever but I do think that it is probably the reason why today I not only respect them but I turned out pretty decent.
I have a very strong temper and I know that I would probably done very wrong things when I was a teenager if my parents didn't know how to discipline me.
It's a matter of preference and how your child personality fits in the whole process.
Now if you as parent are beating the crap out of your child to the point that they get bruses and once in a while you have to run them to the hospital because the injuries were bad then you are confused. What you are doing is called "ABUSE" and is way different than just a little smacking here and there when your child is not behaving.
Another thing is some parents thing that it is better to verbally abuse the child instead of spanking. Totally wrong. those words will stick in your child's mind and he/she will remember those forever.
For the parents that never spank their children and think that talking is all they need to do. Watch it! you might just be giving your kid the impression that he/she can do whatever she wants and all you will do is a litte talk.
Good luck to all you parents out there. Raising a child is not easy task. =D