[Ensorceled]

Exactly. It doesn't even have to necessarily say "this is wrong" ... just something that causes you to engage with the example as potentially unreliable or not the best solution.

"The traditional way to solve this problem ..."

"Other tutorials suggest something like the following ..."

It's just sadistic to give an example that doesn't work and then I waste time looking for a syntax error or typo that doesn't exist.