\includegraphics certain PDF files (for example this SVG converted with Inkscape), the output produced by LuaLaTeX or PDFLaTeX will be such that when the page containing the picture is printed with CUPS, the whole page will be rasterized which looks like the bottom example in the picture below (I have the CUPS option to "force rasterization" which produces the same bad printout with any page so CUPS or my configuration of it is surely partly to blame). The first line is the same page without that PDF included. Other PDFs work just fine, as do all raster images (which is kind of paradoxical).
These are scans of the result of course, so please excuse the bad quality. You should still be able to see the wavy look of the "l"s and other slanted vertical lines.
Here for a comparison the rasterized output as a PDF:
I experimented a bit with different PDF viewers and printing to PDF instead of wasting paper. Here is what okular produced:
And this is acroread at the same zoom level:
If you watch closely, acroread might just have a slight edge ;)
Even when forcing acroread to "print as image" as I suppose the "force rasterization" option is named here, the result looks much better:
I don't know if it looks like the insane 2400 dpi it's supposed to be but still (these pictures are printed at about the text size of