The easy passwords (for today) were already filtered out. The idea was to future-proof it by recording how hard they were. Rounding to, say, whole numbers still leaks information, but a bit less. So now everything from [13.5,14.5) map to 14, that's still smaller than [0,+inf]. You could use some sort of hidden value mapping them to grades that aren't obviously mappings of entropy (like A, B, C, D). It indicates that there's something about them, but without seeing a table mapping [10,12] -> C you don't know exactly what. That's still a point for data to leak, though, should the mapping be discovered (encoded elsewhere in your database or somewhere in your code).