IMO the only thing you can assume is that the person who wrote the comment wasn't actively trying to deceive you. You should treat all documentation, comments, function names, commit messages etc with a healthy dose of scepticism because no one truly has a strong grip on reality.

Right, unlike code (which does what it does, even if that isn't what the writer meant) there's no real feedback loop for comments. Still worth internalizing the info based on that IMO.

"This does X" as a comment when it in fact does Y in condition Z means that the probability you are looking at a bug goes up a bit! Without the comment you might not be able to identify that Y is not intentional.

Maybe Y is intentional! In which case the comment that "this is intentional" is helpful. Perhaps the intentionality is also incorrect, and that's yet another data point!

Fairly rare for there to be negative value in comments.