You can get my USHCN C++ code (which shows the amount of fake data) here. It is simple enough to figure out and similar to the GHCN code. It downloads and runs much faster than the GHCN daily calculations. You can do the whole thing in a few minutes.
cd into the newly created ushcn directory
ln -s ../ushcn.exe
ln -s ../configure
./ushcn.exe US_final.tavg > US_final.csv
./ushcn.exe US_tob.tavg > US_tob.csv
./ushcn.exe US_raw.tavg > US_raw.csv