back-alley vs sly

back-alley

adj
  • Occurring away from publicity, or in mean surroundings; backstreet. 

sly

adj
  • Done with, and marked by, artful and dexterous secrecy; subtle 

  • Light or delicate; slight; thin. 

  • Artfully cunning; secretly mischievous; wily. 

  • Dexterous in performing an action, so as to escape notice 

adv
  • Slyly. 

How often have the words back-alley and sly occurred in a corpus of books? (source: Google Ngram Viewer )