Why are so many of my patches out of tune ?

[rjay]

Ever since I first bought my Polar I've been annoyed by the number of patches that have bad tuning. Not all of them, but a significant amount, maybe even a majority.

I've just been checking them with Autotune, and there seems to be no pattern to it. A below middle C (on on patch, for example) is 10cents sharp then E above middle C is 15cents flat. That's only a fifth away so playing chords sounds horrible and because it's not constant across the patch you can't just adjust the tuning for the patch.

What would cause this ?