If you are encountering strange font substitutions in Acrobat DC, here's a quick fix below. 

Start by deleting C:\Windows\System32\FNTCACHE.DAT

Reboot the computer.

View the PDF in Acrobat DC. The PDF in question will display the substituted font in Wingdings. 

Change the Zoom level. 

Previously scrambled PDFs should be viewable normally and the Wingdings should be normal text.