i hated them as a kid for obvious reasons but as i grew up i actually appreciated quite a bit the fact that i got my ass spanked.
it didn't happen frequently, but the threat of it was enough to keep me out of the worst trouble i had the potential to get into

spanking has been shown not to help kids and can actually do mental damage ...sooo #themoreyouknow

*can* does not mean *will*
I've known several kids both while growing up and now as an adult who could use a good smack in the back of the head frankly, some people are just assholes, and kids turn that shit up to 11
but again, the THREAT of the spanking always did about a million times more then the actual act
nevermind the potential disasters it averted because kids don't know how to think of consequences

as a kid my thought was "oh a creek! i wanna go swimming.... but i better not go swimming in the creek or i'll get my ass whooped"
nevermind the very real threat of snakes, spiders, broken glass and swift currents

and finally, "has been shown" source please, i'd like to see where you got the information