The desire to be the perfect Mom ... be careful not to be lured into the pleasing deception of that.
There's also the danger of flirting with "holier than thou" statements in threads like these, even if unintended.
There were issues from my own childhood that I never wanted my kids to feel subjected to. Spanking was one of them. So I made conscious choices I felt would facilitate a certain result in my kids' lives. I read, noted and put into practice positive information from books that were popular when my kids were going through different developmental stages.
I now have two young people stepping out into their adult lives and it's interesting to note that what "worked" for one child did not appear to "work" for the other. It was always a balancing act to understand each child and offer what I believed they needed at the time. And despite all that's great about what you do in your job as a parent, each child needs to rebel in their own way in order to help establish their independence, and will complain about SOMETHING that you did or didn't do. Each will likely feel that there was something challenging about their upbringing. No matter how "perfect" you try to get it, or how diligently you apply some magic parenting formula.
My point I guess, simply put, is there is no formula. I believe that love, communication and mutual respect are the cornerstones of every relationship, including with your kids, but after that some of parenting is just "winging it" and hoping you are doing the right things for your family.
As for the OP, I won't criticize someone who feels that there is an occasional reason to spank as a means to communicate a consequence. For example, I gave my two year old son a spank when he continually wanted to run away from me on walks, potentially into traffic or other dangerous situations. It was effective when words couldn't deliver that message and he lacked the reasoning capacity to control his own behaviour. I would define an acceptable spank as a "hand-to-bum" shot on a clothed bottom.
Let's be clear though - I don't condone any kind of abuse - spankings are generally more about parents venting their own frustrations on a child rather than teaching any objective lessons. I agree those can leave indelible marks that last a lifetime ...