After running around doing some test shots with my arriving-much-too-late K-3, all I can say is its either user error, or a bad lens, or both on your part. Sorry.
I'm looking at the out of camera JPGs this beast is kicking out for me and loving everything about the camera. I'll have to throw my old kit lens from the K-x on it and see if I notice anything different, but so far its passed the test with the three lenses I've tried it out with (my Sigma 10-20, and new Samyang 35 f/1.4 and 85 f/1.4's).
These are both from my new Bower 35mm f/1.4, shot out my apartment window. I'm not even sure if I opened the window up for this.
One's a straight out of camera JPG, the other is the DNG file where I simply changed it to a JPG and uploaded without touching the thing.
35mm, f/10, 1/125 second, ISO 200, default camera settings as far as I know (I don't think I'd mucked with anything yet - I'm kind of scared to, the cameras intimidating coming off my K-30!)
First is the SOOC JPG, second is the DNG converted to JPG with no alterations other than format.