So I've had this issue with a pdf, I tried to export it CMYK, RVB, interactive pdf, regular pdf, with tons of different other options, the text was still very aliased.
I decided to take it back from scratch, openned a new document with the same size, and copied/pasted element after element from the old one to the new one, exporting as pdf between each copy/paste. The first exports went really well, the render was great… until I pasted a vector element that was applied with a blending mode (overlay).
When I switched it to normal, the pdf export was smooth again. Tried every blending mode, everyone makes the text jaggy. Switch back, it's ok. So I'm 100% sure that this comes from blending modes, as opposed to what I could have read on other forums.
This is a request, please, InDesign team, take care of this problem, this is quite annoying in many cases.
Thank you for your attention!
Twitted here as well : https://twitter.com/grinderlabs/status/448381486627311616
To minmize the possibility of rasterizing or outlining text when transparency is flattened, keep the text above any transparent objects. Blending modes, along with most effects, use transparency.
You can also minimize the risk by exporting the PDF with live transparency, which is supported in Acrobat 5 or higher compatibility.