I think that's the tricky thing. I'm not saying it's not useful when it is, but you really do need a keen and skeptical eye to be able to know. The problem kind of reminds of bloom filters, such that they're useful for situations when you want to know something might exist or definitely does not exist in a set. Exact truth has some level of permissible error rate, as it does in any situation, but definitely wrong is pretty important to know about.