Ok. Not fonts then. Here are a couple of things to look in to. First, see if it views like this at 100%.
Then, in preferences there are some settings. Go to Edit>Preferences>Page Display. Make sure the resolution is site properly for your monitor. Then go to "Rendering" and try a couple of the "Smooth text" options to see if one works.
If that doesn't work:
I'm assuming that the text having the issue is selectable in Reader? Just want to be sure your software isn't rendering it as an image.
What steps are you taking to create the pdf file? Have you checked settings in that process?
~graffiti,
Thank you for sticking with this. I noticed that Adobe classified the characters as "AutoCAD SHX Text". This jogged my memory about AutoCAD SHX Fonts and 'finickiness' in working well with other pieces of software. This allowed me to search for the proper terms and I found the solution:
https://knowledge.autodesk.com/support/autocad-electrical/troubleshooting/caas/sfdcarticles/sfdcarticles/Choppy-or-distorted-display-in-Adobe-Reader.html
The solution turned out to be one of the Rendering options > "Smooth line art".
This makes sense, because you informed me that the characters were not, in fact, text, but outlines which are probably considered to be more image based.
Thanks again!
~Z