8. It is too easy for a frustrated parent to cross the line from spanking to abusing. Unfortunately, by the time the smoke clears, many parents have crossed the line from spanking to hitting, shaking, slapping and other forms of child abuse. Source: ActiveParenting.com
This is the reason why parents who advocate spanking suggest to NEVER spank your child when you are angry. Some parents suggest to calm down first and not spank when your emotions are high.
Of course, when you have calmed down, you probably have by then thought of a better approach to handle the situation than spanking.
We all want our child to build self-confidence. However, Spanking goes counter to helping your child build self-confidence.