Very true. And close to the knuckle... A few weeks ago, I found a small but very noticeable dent in my car door, clearly caused by careless, if not malicious, opening of somebody else's door in a car park. It annoyed me such much I decided to get it fixed and had it done by a 'paintless dent removal' process, whereby it is tapped out from the other side.
It was incredibly successful, the dent has vanished, with no disruption to the paint finish. But I know for sure, if I'd tried to do it DIY, it would have ended badly.
Knowing where to tap is indeed a skill worth paying for.