Everyone is entitled to their opinion. And no one said spanking was the most reasonable way to deal with bratty kids. It isn't unreasonable, however, regardless of  Ms. Martin's opinion. 

My parents spanked me on occasion; when I deserved it. Always on the butt and looking back never hard. My mom used the wooden spoon sometimes. She feels bad but my brother and I joke about timing the butt thrust forward to make her miss. That's literally the only lasting memory. 

We have a great relationship with both our parents and don't have anger management issues, didn't get into fights in school, bully other kids, abuse our own children or any of the negative nonsense people like Ms. Martin like to paint across the entire swath of corporal punishment.

Common sense goes a long way. Seems obvious. Sadly it's not. Do what you think is best and use discretion. It's actually pretty simple.