I was abused as a kid, and ended up in foster homes/group homes because of it. Despite that, I still believe that there is a difference between ordinary spanking and discipline, and abuse. However, I have read that abused children often turn out to be abusing parents, and that is one of my greatest fears. It disgusts and angers me when I am in a grocery store or other public place, and see some aggravated parent smack their kid for asking a question or begging for some candy that they see in the check-out line.
In my opinion, there is such a thing as acceptable spanking:
1) Should never be done out of anger or knee-jerk reaction. If need be, wait a few minutes, take a deep breath, whatever, until you can do it with rational thought.
2) Should never involve striking any body part but the buttocks, no slapping of the face or striking any other body part.
3) Should always be done with a bare hand, not with a paddle or any other object that amplifies the impact.
4) Should never involve the removal of clothing, this adds an element of shame and possible impropriety that should not be involved in disciplinary action.
5) Should always be preceded by a lecture on what the child has done wrong, so the child understands what the spanking is for. Not to be crass about it, but the equivalent of putting a puppy's nose to the wet spot when training them to go out. Otherwise they think they are being hit for whatever their last prior action was, instead of what the discipline is for.