That is a lot of dust spots (in addition to the bigger blobs your are concerned about). Are you using the k-5 dust removal system at startup? Menu>tools>Dust Removal>startup action
That should get rid of most of the smaller spots. The bigger ones I agree look more droplets than dust. Has the camera been open in rain/mist or anything? Regardless, I agree with the above, they are on the sensor.
Dust removal procedure in order:
- Use the camera dust removal system (shaker) There is a menu setting to turn on/off. If you have dust run this several times in a row and then check for dust again. I leave mine on "run on startup" and think that is best so you don't have to worry about it. The k-5 system is excellent and I rarely see dust spots anymore.
- Use a 'rocket blower' or equivalent to blow off anything the shaker will not get rid of. Do not use compressed air or canned air. Some folks report it is OK to use canned air if you are careful, but personally I'm not taking any chances.
- Another suggestion from a poster on PF was to use a fine art brush and spray it with canned air (the brush) this causes a static charge on the brush and helps to pick up difficult dust.
- Use a wet cleaning kit. This is the last resort, and on two cameras with over 25,000 actuations in all kinds of environments I've never had to use one yet. Get this if all else fails but don't go there unless you are sure you need it.
- Send in for professional cleaning. Pentax extended warranty (in the US) includes one 'free' cleaning. Not sure about anywhere else.