To take one of the classics of bad copy-past examples: "If the 'use-PHP-with-MySQL' example you copied is stupid, works, and also causes your production database to be hacked due to SQL-injection, it probably was stupid"

The problem is to tell the difference between "ugly stupid" and "dangerous stupid"

“If it’s stupid but it works, it’s still stupid and you got lucky.”

"works" is a nuanced word.

The saying can be wonderfully pithy or terribly destructive depending on people's understanding of the word.

The problem is with defining "works". If your code "works" with ten test entries in a DB when you test the happy path, it doesn't mean that it really works in production, with real load and real attack attempts on it.