Last week I helped a co-worker with some flaky tests, where the code and tests were generated from one of the models. While looking at how one of the tests work, I'd spotted a place in the code where a boolean condition was backwards in a way a human would never have written (and on top if it, there was a confidently-incorrect block comment above it so it was easy to assume it was correct) - so even if he'd fixed the test's flakiness, it would end up always failing instead of sometimes failing. He'd spent hours trying to figure out what was going on.