Working in InDesign my placed vector logos from Illustrator are fuzzy after converted to PDF. Why?
Are you sure they're native graphics in the inDesign document?
If not it likely means the link has broken. Look in your links panel to make sure everything is hunky-dory. Yellow triangle – source not found. Red circle – source file has been moved after placing.
Either that or they've been scaled beyond their original size.
Last thing to check would be your compression settings when exporting to PDF. make sure they're appropriate for screen/print
Screen shots would help.