As part of the work to constrain the expected false positive rate for the upcoming PLATO 2.0 mission, we have been examining the certified false positives within the Kepler catalogue, comparing this with the confirmed exoplanets and the exoplanet candidates from the same source. We have been trying to reproduce the observed trends over planet class and orbital period through suitable population synthesis methods. Considering false positives with either a “significant secondary” or “centroid offset” flags (or both), there is a disparity between the observed trends and simulated trends if a limiting magnitude for background stars, set by zodiacal dust, of ≈ Mkp = 21 is assumed. We consider various explanations for this, including Kepler observing variations from systems fainter than the zodiacal dust, and blended transits from exoplanets contributing to the false positive tally.