Why is text appearing as dots when using Acrobat to view or plot PDFs created by AutoCAD?

I'm guessing the fonts are not embedded in the PDF from AutoCAD. Other PDF viewers may be substituting the missing font, but Acrobat is not. Check your export or "save-as" settings when creating your PDF from AutoCAD, look for an option to embed the fonts. You can see if your fonts are embedded in Acrobat by going to File> Properties> Fonts, they should all say embedded, or embedded subset. You could try changing your Acrobat preferences> Page display> use local fonts, this may help the screen view but it won't properly embed the missing fonts.