Yep, as I said in the post, InDesign is smart enough to show the true story with Overprint Preview. It’s odd that InDesign “gets it,” but Acrobat doesn’t. This has now been mentioned in an Adobe technote here: . There’s no workaround in Acrobat; your only hope is to use InDesign as the viewer. Of course, you don’t want to have to do that with every PDF you receive! It might be a good approach to any Quark-generated PDFs, though, if you’re paranoid. And weird stuff like this does tend to make us paranoid, doesn’t it?

QuarkXPress does not handle late-model PDFs well. I’d suggest opening the original PDF in Acrobat, then using Advanced>PDF Optimizer to save as an Acrobat 4.0 file, without changing any resolution or compression settings, then try that in QuarkXPress. What original application was used to make the PDF?
If that doesn’t fix the overprint issue, use Tools>Advanced Editing>TouchUpObject tool to select the copy, right-click and choose Edit Object(s) to open the text in Illustrator. WARNING: if you don’t have the font, this won’t work. Change the overprint attribute in Illustrator (Window>Attributes), choose File>Save to write it back into the PDF, then resave the PDF.

Good luck!

It’s just so odd that Acrobat highlights the area as overprinting, generates separations that clearly exercise the OP instruction, but won’t freaking display the effect. Ah, well. It’s a sign: don’t use Quark!