>I'm 1000% sure there are gurus who could whip up a script to overcome this. But its kind of one of those things where you don't have to outrun the bear, you have to outrun your friend running next to you. It makes your sensitive documents just that much less likely to be scanned/found.

Security through obscurity is stupid:

    gs -sDEVICE=tiffscaled24 -dNOPAUSE -dBATCH -dSAFER \
       -sOutputFile=filename.tiff \
       filename.pdf
    tesseract filename.tiff filename.txt

All you need is ghostscript and tesseract. Both are an apt-get away.