During bug fixing some time ago I came across a comment that was plain wrong - it described the effect of the code as being the opposite of the actual effect. After spending considerable time "fixing" the code I discovered that it had in fact been correct and that the bug I was looking for was in a completely unrelated piece of code.
In that particular case there was no need for the comment. One reason the code took considerable time to "fix" was that all the identifiers were "wrong". Without the comment the code was correct, consistent and clear. However, the comment was plausible and in the context of the symptoms of the bug the code could well have been incorrect.
Perl's payment curve coincides with its learning curve.