See this detailed summary and report, also with some opinions of the OP author expressed:-
http://forum.xitek.com/showthread.php?threadid=812805
(in Chinese, Google-translated English page here.)
Indeed, a very nice summary is compiled. Images are posted of which all are taken with brand new K-5 units with the defective "scratched" sensors (actually the AA filters of) for what some different Pentaxian victims have reported. In the posted photos, the defect is clearly shown and the scratches or stains (or whatsoever it is called, but it is NOT dust!) become very visible when just smaller apertures at or beyond f/11 are used.
Last but not least, I am fully agreed with the OP that it is a case showing the true value and power of the Internet. Without it, those manufacturing and QC issues would never be got known for the public (and so quickly) and the consumers would not get their replacement units so "easily" than ever before.
The poster has also kindly made some very good suggestions to Pentax for checking for the production line for whether there is anything wrong in the manufacturing process, which resulted in damage/contamination to the sensors/AA filters and their optical surface(s), no matter it is related to the machines and/or by the labours.
But anyway, I am almost sure that Hoya would just not listen, they will continue to do things on their own and avoid to admit any problem nor to proactively find out the root causes upon reported issues and not even to mention about to take preventive measures so that the same problems should not happen (and happen) again! >:-(
Read Also:-
Scratched "Sensor" Cases of the K-5 Units - Quality Issue of the AA Filters Manufactured by Pentax?
Scratched Sensors of Brand New K-5 Units
1,000 Signatures of the Pentax SDM Petition Online!
Pentax Service Sucks Everywhere in the World!