FWIW, which may be nothing, I always use Preflight>Fixups>Convert to Gray in Acrobat. Seems to work when PitStop and other tricks fail.
So, if I do the Dotspy method, since the 1-bit tiffs are already screened, won't it essentially give me a grayscalerosette pattern?
... in my mind, if you set up a good workflow to convert and/or merge crap like this, you just always use it and save yourself some headaches....
Here's a page from the PDF for anyone who wants to see what's going on. I was using Acrobat 8.2.1 with Pitstop 7.51. I do have a newer version (Pitstop 10, update 3), but haven't been using it because I dislike Acrobat X's interface. I did not try to convert to gray with the newer one - just the older one.https://dl.dropbox.com/u/33794637/grayweird.pdf
It's got something to do with the text being a form. I haven't got it completely figured out yet.