Originally posted by Kennod This looks like the dreaded sensor stain
NO it does not!
Dust is a fact of life and dust will deposit itself on sensors of ALL exchangeable lens cameras. You better get used to it. It is unavoidable. But unfortunately when it is found on a PENTAX cam it will strike fear in its owner to the end of civilization and will always be associated with sensor stain. You are one of those people who has succumbed to this dreaded fear. Just clean it off and all will be fine.
By the way, the sensor is more robust than manufacturers of sensor cleaning kits want you to know because then they can sell you a $3.00 soft nylon brush for $25.00. The filter atop that sensor is incredible hard and is not easily damaged if you proceed with intelligent care. It has to be, because manufacturers know that it has to withstand regular careful cleaning over many years.
Your spots in the posted pic is nothing more than dust, crap, manure, fluff or what ever you wish to call it.
Greetings