Disappointed with K-30.

No, I don't think you can keep humid air out, without the camera being waterproof.  I believe the humidity inside those camera phones is the same as the humidity inside your DSLR.  I think the only difference is how the device is presented to the warm, humid air.   A DSLR is a much larger, more complicated device that is going to warm up more slowly and has more moving parts where air can be trapped.  I don't think Pentax wanted, tried or should have made it an air-tight device.