[emeril]

I suppose I'd just save the pdf to tiff/png then remake back into a pdf from there to avoid printing and scanning?

if really paranoid, I suppose one could run a filter on the image files to make them a bit fuzzy/noisy

[maximilianthe1]

I think "Print to PDF" would be easiest

[bawolff]

I'd worry print to pdf might be ineffective. I think rasterizing is the way to go.