My personal opinion is that spanking should be saved for those rare occasions when nothing else works and you really need to get your point across. However, I would explain why they are getting spanked first so they understand it's not just because you feel like venting your own anger on them.

I believe that if a child is spanked too often it no longer matters to them.  Also,  sometimes a parent trying to prove a point that it "really does hurt" are the ones that go to extremes and it turns in to abuse.

Everyone is different everyone has their opinions on this subject. I was abused as a child so I know what it feels like to be "spanked" aka "beat". Not knowing why was the worst part.