How does a canary string provide any certainty one way or the other? It's easy to consider a false positive scenario: a blog post talking about canary strings,

How does a canary string provide any certainty one way or the other? It's easy to consider a false positive scenario: a blog post talking about canary strings, what they do, and then saying "here's the BIG-Bench canary string". A false-negative is similarly easy to consider: an unscrupulous employee could scrub the string itself from the training set but keep the rest of the benchmark data. I expect people more clever than me have spent more than the three minutes I did thinking on it, so I'm genuinely curious as to how the two scenarios above are protected against. From my limited understanding, though, it feels like there's just an honor system involved.