Well, most codecs become "transparent" for normal people at some point, see
wikipediaIn other words: Most people can't distinguish between e.g. 256 kbps and 320 kbps. Even not between 256 kbps that were upscaled to 320 kbps and real 320 kbps. That's why it might be confusing if "Fakin' The Funk?" reports a file as "fake" when it obviously sounds brilliant.
And yes: There *might* be false positives.
Unfortunately, it is NOT possible to get a 100% accurate bitrate identified from the pure audiostream...
But in case you want to have only the highest quality that's possible, and 256 kbps is not enough for your ears :-), then you might want to allow to report those "fakes" and check yourself!