I've read the first book awarded a Worthy® - The Dark Page by Sam Fuller. It turned out to deserve the award. Stock characters from a 1940s New York tabloid and the Bowery and overheated "The Front Page" dialogue but I enjoyed the central mystery.
Here are a few of the non-worthies from the first 50 Harlequins.
Harlequin 8 - August 1949
Harlequin 8 back