above-board vs smooth-spoken

above-board

adj

  • In open sight; without trick, concealment, or deception. 

adv

  • Honestly; openly. 

smooth-spoken

adj

  • Plausible. 

  • Having a pleasant-sounding voice. 

  • Flattering. 

How often have the words above-board and smooth-spoken occurred in a corpus of books? (source: Google Ngram Viewer )